vfmt: change all '$expr' to '${expr}' (#16428)

vlib/builtin/js/map_test.js.v

@@ -502,10 +502,10 @@ fn test_map_str_after_delete() {
 		'second': 2
 		'third':  3
 	}
-	osm := '$m'
+	osm := '${m}'
 	m.delete('second')
-	nsm := '$m'
-	println('m: $m')
+	nsm := '${m}'
+	println('m: ${m}')
 	assert osm == "{'first': 1, 'second': 2, 'third': 3}"
 	assert nsm == "{'first': 1, 'third': 3}"
 }
@@ -655,7 +655,7 @@ fn test_rune_keys() {
 	m[`@`] = 7
 	assert m.len == 3
 	println(m)
-	assert '$m' == '{`!`: 2, `%`: 3, `@`: 7}'
+	assert '${m}' == '{`!`: 2, `%`: 3, `@`: 7}'
 
 	/*
 	mut a := []rune{}
@@ -752,7 +752,7 @@ fn test_map_assign_empty_map_init() {
 	a = {}
 	println(a)
 	assert a == map[string]int{}
-	assert '$a' == '{}'
+	assert '${a}' == '{}'
 }
 
 fn test_in_map_literal() {
@@ -947,11 +947,11 @@ fn test_map_set_fixed_array_variable() {
 	mut m := map[string][2]f64{}
 	m['A'] = [1.1, 2.2]!
 	println(m)
-	assert '$m' == "{'A': [1.1, 2.2]}"
+	assert '${m}' == "{'A': [1.1, 2.2]}"
 
 	mut m2 := map[string][2]f64{}
 	arr := [1.1, 2.2]!
 	m2['A'] = arr
 	println(m2)
-	assert '$m2' == "{'A': [1.1, 2.2]}"
+	assert '${m2}' == "{'A': [1.1, 2.2]}"
 }