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.

rss/classes/privacy/provider.php

@@ -51,7 +51,7 @@ class provider implements
      * @param   collection $collection The initialised collection to add items to.
      * @return  collection A listing of user data stored through this system.
      */
-    public static function get_metadata(collection $collection) : collection {
+    public static function get_metadata(collection $collection): collection {
         $collection->add_subsystem_link('core_userkey', [], 'privacy:metadata:core_userkey');
 
         return $collection;
@@ -63,7 +63,7 @@ class provider implements
      * @param int $userid The user to search.
      * @return contextlist $contextlist The contextlist containing the list of contexts used in this plugin.
      */
-    public static function get_contexts_for_userid(int $userid) : contextlist {
+    public static function get_contexts_for_userid(int $userid): contextlist {
         $sql = "SELECT ctx.id
                   FROM {user_private_key} k
                   JOIN {user} u ON k.userid = u.id