MDL-65292 style: Fix all function declarations white space

This has been generated running the following Sniffs, all
them part of the Moodle's CodeSniffer standard:
- PSR12.Functions.ReturnTypeDeclaration
- PSR12.Functions.NullableTypeDeclaration
- moodle.Methods.MethodDeclarationSpacing
- Squiz.Whitespace.ScopeKeywordSpacing

All them are, exclusively, about correct spacing, so the changes
are, all them, only white space changes.

Only exceptions to the above are 3 changes what were setting the
return type in a new line, and, when that happens, the closing
parenthesis (bracket) has to go to the same line than the colon.

lib/classes/date.php

@@ -710,7 +710,7 @@ class core_date {
      * @return string
      * @author BohwaZ <https://bohwaz.net/>
      */
-    public static function strftime(string $format, $timestamp = null, ?string $locale = null) : string {
+    public static function strftime(string $format, $timestamp = null, ?string $locale = null): string {
         // Moodle-specific modification. For the IntlDateFormatter we need to use unix-style locale
         // from the string 'locale' even for Windows, so we can neither use moodle_getlocale().
         // nor rely on the setlocale() use below. We also ignore $CFG->locale because it can use