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.

admin/tool/uploadcourse/tests/course_test.php

@@ -1739,7 +1739,7 @@ class course_test extends \advanced_testcase {
      *
      * @return core_customfield_generator
      */
-    protected function get_customfield_generator() : \core_customfield_generator {
+    protected function get_customfield_generator(): \core_customfield_generator {
         return $this->getDataGenerator()->get_plugin_generator('core_customfield');
     }
 
@@ -1753,7 +1753,7 @@ class course_test extends \advanced_testcase {
      * @return \core_customfield\field_controller
      */
     protected function create_custom_field(\core_customfield\category_controller $category, string $type, string $shortname,
-            array $configdata = []) : \core_customfield\field_controller {
+            array $configdata = []): \core_customfield\field_controller {
 
         return $this->get_customfield_generator()->create_field([
             'categoryid' => $category->get('id'),