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/dml/tests/dml_table_test.php

@@ -35,7 +35,7 @@ class dml_table_test extends \database_driver_testcase {
      *
      * @return  array
      */
-    public function get_field_select_provider() : array {
+    public function get_field_select_provider(): array {
         return [
             'single field' => [
                 'tablename' => 'test_table_single',
@@ -102,7 +102,7 @@ class dml_table_test extends \database_driver_testcase {
      *
      * @return  array
      */
-    public function extract_from_result_provider() : array {
+    public function extract_from_result_provider(): array {
         return [
             'single table' => [
                 'fieldlist' => [