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/tests/persistent_test.php

@@ -183,7 +183,7 @@ class persistent_test extends advanced_testcase {
     /**
      * Test creating persistent instance by specifying record ID in constructor
      */
-    public function test_constructor() : void {
+    public function test_constructor(): void {
         $persistent = (new core_testable_persistent(0, (object) [
             'idnumber' => '123',
             'sortorder' => 1,