update: insert donation links based on FUNDING.yml

GitHub has specified FUNDING.yml, a file to include in a git repo for
pointing people to donation links.  Since F-Droid also points people
to donation links, this parses them to fill out Donate:
and OpenCollective:.  Specifying those in the metadata file takes
precedence over the FUNDING.yml.  This follows the same pattern as how
`fdroid update` includes Fastlane/Triple-T metadata.  This lets the
git repo maintain those specific donations links themselves.

https://help.github.com/en/articles/displaying-a-sponsor-button-in-your-repository#about-funding-files

The test file was generated using:

```python
import os, re, yaml

found = dict()
for root, dirs, files in os.walk('.'):
    for f in files:
        if f == 'FUNDING.yml':
            with open(os.path.join(root, f)) as fp:
                data = yaml.safe_load(fp)
            for k, v in data.items():
                if k not in found:
                    found[k] = set()
                if not v:
                    continue
                if isinstance(v, list):
                    for i in v:
                        found[k].add(i)
                else:
                    found[k].add(v)

            with open('gather-funding-names.yaml', 'w') as fp:
                output = dict()
                for k, v in found.items():
                    output[k] = sorted(v)
                yaml.dump(output, fp, default_flow_style=False)
```

tests/funding-usernames.yaml

@@ -0,0 +1,197 @@
+bad:
+  - "Robert'); DROP TABLE Students; --"
+  - ''
+  - -a-b
+  - '1234567890123456789012345678901234567890'
+  - ~derp@darp---++asdf
+  - foo@bar.com
+  - me++
+  - --me
+bitcoin:
+  - 3Lbz4vdt15Fsa4wVD3Yk8uGf6ugKKY4zSc
+community_bridge: []
+custom:
+  - bc1qvll2mp5ndwd4sgycu4ad2ken4clhjac7mdlcaj
+  - http://www.roguetemple.com/z/donate.php
+  - https://donate.openfoodfacts.org
+  - https://email.faircode.eu/donate/
+  - https://etchdroid.depau.eu/donate/
+  - https://f-droid.org/about/
+  - https://flattr.com/github/bk138
+  - https://gultsch.de/donate.html
+  - https://jahir.dev/donate
+  - https://kodi.tv/contribute/donate
+  - https://link.xbrowsersync.org/cryptos
+  - https://manyver.se/donate
+  - https://paypal.me/DanielQuahShaoHian
+  - https://paypal.me/deletescape
+  - https://paypal.me/freaktechnik
+  - https://paypal.me/hpoul
+  - https://paypal.me/imkosh
+  - https://paypal.me/paphonb
+  - https://paypal.me/vocabletrainer
+  - https://pendulums.io/donation.html
+  - https://play.google.com/store/apps/details?id=de.dennisguse.opentracks.playstore
+  - https://play.google.com/store/apps/details?id=eu.faircode.email
+  - https://raw.githubusercontent.com/Blankj/AndroidUtilCode/master/art/donate.png
+  - https://raw.githubusercontent.com/CarGuo/GSYGithubAppFlutter/master/thanks.jpg
+  - https://raw.githubusercontent.com/GanZhiXiong/GZXTaoBaoAppFlutter/blob/master/preview_images/thanks.png
+  - https://seriesgui.de/whypay
+  - https://transportr.app/donate/
+  - https://www.bountysource.com/teams/nextcloud/issues?tracker_ids=38838206
+  - https://www.donationalerts.com/r/blidingmage835
+  - https://www.hellotux.com/f-droid
+  - https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=8UH5MBVYM3J36
+  - https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=E2FCXCT6837GL
+  - https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FMLNN8GXZKJEE
+  - https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=K7HVLE6J7SXXA
+  - https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=ZD39ZE7MGEGBL&source=url
+  - https://www.paypal.me/SimpleMobileTools
+  - https://www.paypal.me/TheAlphamerc/
+  - https://www.paypal.me/avirias
+  - https://www.paypal.me/btimofeev
+  - https://www.paypal.me/enricocid
+  - https://www.paypal.me/gsnathan
+  - https://www.paypal.me/nikita36078
+  - https://www.paypal.me/sahdeep
+  - https://www.paypal.me/saulhenriquez
+  - https://www.simplemobiletools.com/donate
+  - https://www.youtube.com/watch?v=ZmrNc1ZhBkQ
+  - paypal.me/amangautam1
+  - paypal.me/pools/c/8lCZfNnU0u
+  - paypal.me/psoffritti
+github:
+  - 00-Evan
+  - adrcotfas
+  - afollestad
+  - ar-
+  - BarnabyShearer
+  - CarGuo
+  - cketti
+  - eighthave
+  - emansih
+  - GanZhiXiong
+  - gpeal
+  - hpoul
+  - i--
+  - inorichi
+  - inputmice
+  - jahirfiquitiva
+  - johnjohndoe
+  - kaloudis
+  - kiwix
+  - ligi
+  - M66B
+  - mikepenz
+  - Mygod
+  - paroj
+  - PerfectSlayer
+  - sschueller
+  - tateisu
+  - tibbi
+  - westnordost
+  - x1unix
+  - xn--nding-jua
+  - zenorogue
+issuehunt:
+  - bk138/multivnc
+ko_fi:
+  - afollestad
+  - fennifith
+  - inorichi
+  - mastalab
+  - psoffritti
+liberapay:
+  - ActivityDiary
+  - AndStatus
+  - BM835
+  - Briar
+  - DAVx5
+  - F-Droid-Data
+  - Feeel
+  - Fruit-Radar-Development
+  - Gadgetbridge
+  - GuardianProject
+  - Hocuri
+  - KOReader
+  - Kanedias
+  - Kunzisoft
+  - MaxK
+  - NovaVideoPlayer
+  - Phie
+  - Rudloff
+  - Schoumi
+  - Syncthing-Fork
+  - TeamNewPipe
+  - Telegram-FOSS
+  - Transportr
+  - Varlorg
+  - Wesnoth
+  - ZiiS
+  - ar-
+  - bk138
+  - btimofeev
+  - bubblineyuri
+  - dennis.guse
+  - developerfromjokela
+  - devgianlu
+  - eneiluj
+  - experiment322
+  - fdossena
+  - fennifith
+  - freaktechnik
+  - gsantner
+  - hisname
+  - hsn6
+  - iNPUTmice
+  - inputmice
+  - k9mail
+  - matrixdotorg
+  - mmarif
+  - moezbhatti
+  - proninyaroslav
+  - quite
+  - renyuneyun
+  - rocketnine.space
+  - sanskritbscs
+  - sschueller
+  - sschueller/donate
+  - stefan-niedermann
+  - tasks
+  - teamkodi
+  - thermatk
+  - tom79
+  - wallabag
+  - westnordost
+  - whyorean
+  - wilko
+  - xbrowsersync
+  - yeriomin
+  - zeh
+open_collective:
+  - avirias
+  - curl
+  - libsodium
+  - manyverse
+  - mastalab
+  - tusky
+otechie: []
+patreon:
+  - BaldPhone
+  - Bm835
+  - FastHub
+  - Teamkodi
+  - andrestaltz
+  - bk138
+  - depau
+  - iamSahdeep
+  - ligi
+  - ogre1
+  - orhunp
+  - tiborkaputa
+  - tom79
+  - westnordost
+  - xbrowsersync
+  - yairm210
+  - zenorogue
+tidelift: []