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/xapi/tests/external/delete_state_test.php

@@ -73,7 +73,7 @@ class delete_state_test extends externallib_advanced_testcase {
      *
      * @return  array
      */
-    public function components_provider() : array {
+    public function components_provider(): array {
         return [
             'Inexistent component' => [
                 'component' => 'inexistent_component',
@@ -150,7 +150,7 @@ class delete_state_test extends externallib_advanced_testcase {
      *
      * @return array
      */
-    public function states_provider() : array {
+    public function states_provider(): array {
         return [
             'Existing and valid state' => [
                 'info' => [],