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.

cache/classes/factory.php

@@ -652,7 +652,7 @@ class cache_factory {
      *
      * @return core_cache\administration_helper
      */
-    public static function get_administration_display_helper() : core_cache\administration_helper {
+    public static function get_administration_display_helper(): core_cache\administration_helper {
         if (is_null(self::$displayhelper)) {
             self::$displayhelper = new \core_cache\local\administration_display_helper();
         }

cache/classes/local/administration_display_helper.php

@@ -440,7 +440,7 @@ class administration_display_helper extends \core_cache\administration_helper {
      *
      * @return array an array of the form to display to the user, and the page title.
      */
-    public function action_addstore() : array {
+    public function action_addstore(): array {
         global $PAGE;
         $storepluginsummaries = $this->get_store_plugin_summaries();
 

cache/classes/output/renderer.php

@@ -377,7 +377,7 @@ class renderer extends \plugin_renderer_base {
      *
      * @return string
      */
-    public function additional_lock_actions() : string {
+    public function additional_lock_actions(): string {
         $url = new moodle_url('/cache/admin.php', array('action' => 'newlockinstance'));
         $select = new single_select($url, 'lock', cache_factory::get_administration_display_helper()->get_addable_lock_options());
         $select->label = get_string('addnewlockinstance', 'cache');

cache/classes/privacy/provider.php

@@ -57,7 +57,7 @@ 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 {
         // Data is stored in cache stores.
         $collection->add_plugintype_link('cachestore', [], 'privacy:metadata:cachestore');