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.

mod/chat/chatd.php

@@ -153,7 +153,7 @@ class ChatDaemon {
         }
     }
 
-    public function error_handler ($errno, $errmsg, $filename, $linenum, $vars) {
+    public function error_handler($errno, $errmsg, $filename, $linenum, $vars) {
         // Checks if an error needs to be suppressed due to @.
         if (error_reporting() != 0) {
             $this->trace($errmsg.' on line '.$linenum, $errno);