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.

backup/cc/validator.php

@@ -121,7 +121,7 @@ final class libxml_errors_mgr {
         libxml_clear_errors();
     }
 
-    private function collect_errors ($filename=''){
+    private function collect_errors($filename=''){
         $errors = libxml_get_errors();
         static $error_types = array(
         LIBXML_ERR_ERROR => 'Error'