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.

question/classes/external.php

@@ -223,7 +223,7 @@ class core_question_external extends external_api {
      * @see \qbank_tagquestion\external\qbank_tagquestion_external
      * @todo Final deprecation on Moodle 4.4 MDL-72438
      */
-    public static function  submit_tags_form_returns() {
+    public static function submit_tags_form_returns() {
         return new external_single_structure([
                 'status' => new external_value(PARAM_BOOL, 'status: true if success')
         ]);
@@ -346,7 +346,7 @@ class core_question_external extends external_api {
     /**
      * Returns description of method result value.
      */
-    public static function  get_random_question_summaries_returns() {
+    public static function get_random_question_summaries_returns() {
         return new external_single_structure([
             'totalcount' => new external_value(PARAM_INT, 'total number of questions in result set'),
             'questions' => new external_multiple_structure(