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.

customfield/classes/data_controller.php

@@ -83,7 +83,7 @@ abstract class data_controller {
      * @throws \coding_exception
      * @throws \moodle_exception
      */
-    public static function create(int $id, \stdClass $record = null, field_controller $field = null) : data_controller {
+    public static function create(int $id, \stdClass $record = null, field_controller $field = null): data_controller {
         global $DB;
         if ($id && $record) {
             // This warning really should be in persistent as well.
@@ -123,7 +123,7 @@ abstract class data_controller {
      *
      * @return string
      */
-    public function get_form_element_name() : string {
+    public function get_form_element_name(): string {
         return 'customfield_' . $this->get_field()->get('shortname');
     }
 
@@ -161,7 +161,7 @@ abstract class data_controller {
      *
      * @return string
      */
-    abstract public function datafield() : string;
+    abstract public function datafield(): string;
 
     /**
      * Delete data. Element can override it if related information needs to be deleted as well (such as files)
@@ -186,7 +186,7 @@ abstract class data_controller {
      *
      * @return field_controller
      */
-    public function get_field() : field_controller {
+    public function get_field(): field_controller {
         return $this->field;
     }
 
@@ -224,7 +224,7 @@ abstract class data_controller {
      * @param mixed $value
      * @return bool
      */
-    protected function is_empty($value) : bool {
+    protected function is_empty($value): bool {
         if ($this->datafield() === 'value' || $this->datafield() === 'charvalue' || $this->datafield() === 'shortcharvalue') {
             return '' . $value === '';
         }
@@ -237,7 +237,7 @@ abstract class data_controller {
      * @param mixed $value
      * @return bool
      */
-    protected function is_unique($value) : bool {
+    protected function is_unique($value): bool {
         global $DB;
 
         // Ensure the "value" datafield can be safely compared across all databases.
@@ -262,7 +262,7 @@ abstract class data_controller {
      * @param array $files
      * @return array array of errors
      */
-    public function instance_form_validation(array $data, array $files) : array {
+    public function instance_form_validation(array $data, array $files): array {
         $errors = [];
         $elementname = $this->get_form_element_name();
         if ($this->get_field()->get_configdata_property('uniquevalues') == 1) {
@@ -288,7 +288,7 @@ abstract class data_controller {
      *
      * @return string
      */
-    public function display() : string {
+    public function display(): string {
         global $PAGE;
         $output = $PAGE->get_renderer('core_customfield');
         return $output->render(new field_data($this));
@@ -318,7 +318,7 @@ abstract class data_controller {
      *
      * @return \context
      */
-    public function get_context() : \context {
+    public function get_context(): \context {
         if ($this->get('contextid')) {
             return \context::instance_by_id($this->get('contextid'));
         } else if ($this->get('instanceid')) {