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/classes/message/manager.php

@@ -64,7 +64,7 @@ class manager {
      * @param \stdClass $savemessage
      * @return int
      */
-    public static function send_message_to_conversation(message $eventdata, \stdClass $savemessage) : int {
+    public static function send_message_to_conversation(message $eventdata, \stdClass $savemessage): int {
         global $DB, $CFG, $SITE;
 
         if (empty($eventdata->convid)) {