MDL-76727 core: Allow phpcs configuration to be overridden locally

This change reduces the priority of the shipped phpcs configuration to
allow for local overrides.

This is beneficial in several situations:
- when users wish to apply stricter or additional standards
- when the integration team wishes to trial new rules

.gitignore

@@ -54,5 +54,5 @@ moodle-plugin-ci.phar
 /admin/tool/componentlibrary/docs
 /admin/tool/componentlibrary/hugo/site/data/my-index.json
 .hugo_build.lock
-.phpcs.xml
+phpcs.xml
 jsconfig.json

.grunt/tasks/ignorefiles.js

@@ -39,7 +39,7 @@ module.exports = grunt => {
                 {
                     rule: {
                         _attrs: {
-                            ref: './.phpcs.xml.dist',
+                            ref: './phpcs.xml.dist',
                         },
                     },
                 },
@@ -52,7 +52,7 @@ module.exports = grunt => {
             });
         });
 
-        grunt.file.write('.phpcs.xml', toXML(config, {
+        grunt.file.write('phpcs.xml', toXML(config, {
             header: true,
             indent: '  ',
         }) + "\n");