Fix moderncsqlite errors and rebase onto main (#2832)

This is #2819 but rebased on latest `main`. This PR is against main too
as opposed to the `moderncsqlite` branch.

The main change here is simply:

```go
// add query parameters to the dsn
if strings.Contains(dsn, "?") {
	dsn += "&"
} else {
	dsn += "?"
}

// wait some time before erroring if the db is locked
// https://gitlab.com/cznic/sqlite/-/issues/106#note_1058094993
dsn += "_pragma=busy_timeout%3d10000"
```

### Pull Request Checklist

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submitting your pull request -->

* [x] I have added tests for PR _or_ I have justified why this PR
doesn't need tests.
* [x] Pull request includes a [sign off below using a legally
identifiable
name](https://matrix-org.github.io/dendrite/development/contributing#sign-off)
_or_ I have already signed off privately

Signed off privately.

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

internal/sqlutil/unique_constraint_wasm.go

@@ -17,15 +17,16 @@
 
 package sqlutil
 
-import "github.com/mattn/go-sqlite3"
+import (
+	"modernc.org/sqlite"
+	lib "modernc.org/sqlite/lib"
+)
 
 // IsUniqueConstraintViolationErr returns true if the error is an unique_violation error
 func IsUniqueConstraintViolationErr(err error) bool {
 	switch e := err.(type) {
-	case *sqlite3.Error:
-		return e.Code == sqlite3.ErrConstraint
-	case sqlite3.Error:
-		return e.Code == sqlite3.ErrConstraint
+	case *sqlite.Error:
+		return e.Code() == lib.SQLITE_CONSTRAINT
 	}
 	return false
 }