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/session/memcached.php

@@ -281,7 +281,7 @@ class memcached extends handler {
      * @param   string  $str save_path value containing memcached connection string
      * @return  array[]
      */
-    protected static function connection_string_to_memcache_servers(string $str) : array {
+    protected static function connection_string_to_memcache_servers(string $str): array {
         $servers = [];
         $parts   = explode(',', $str);
         foreach ($parts as $part) {