Defer to phpcs.xml file if present.

[jhedstrom]

• Fixes Defer to phpcs.xml/phpcs.xml.dist when present #311

[jhedstrom]

This probably needs some tests. Also, it may require changes to grunt-phpcs since even passing empty files, that module is still specifying the standard, etc:

Executing: vendor/bin/phpcs --report=full --standard=vendor/drupal/coder/coder_sniffer/Drupal,vendor/drupal/coder/coder_sniffer/DrupalPractice ""

[jhedstrom]

Need to add 2 warnings here:

1. If phpcs paths/dirs are specified in Gruntconfig.js and there is a phpcs.xml file, need to warn that the grunt configs will be ignored.
2. If there is a phpcs.xml file and there is a conflicting standard specified in Gruntconfig.js, warn that this standard should be set to phpcs.xml.

[grayside]

Extra warning-handling requirement noted by @jhedstrom in comment.

[jhedstrom]

@grayside I've added the first warning, but cannot remember how the second warning actually differs.

[jhedstrom]

Hmm, this still needs a bit of work I think. The standard in the phpcs file isn't actually being used as the code in quality.js is still specifying the standard.