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.

notes/classes/privacy/provider.php

@@ -54,7 +54,7 @@ class provider implements
      * @param collection $items a reference to the collection to use to store the metadata.
      * @return collection the updated collection of metadata items.
      */
-    public static function get_metadata(collection $items) : collection {
+    public static function get_metadata(collection $items): collection {
         // The core_notes components utilises the shared mdl_post table.
         $items->add_database_table(
             'post',
@@ -78,7 +78,7 @@ class provider implements
      * @param int $userid the userid.
      * @return contextlist the list of contexts containing user info for the user.
      */
-    public static function get_contexts_for_userid(int $userid) : contextlist {
+    public static function get_contexts_for_userid(int $userid): contextlist {
         global $DB;
 
         $contextlist = new contextlist();