Delete .phpcs cache directory when rolling up to parent

[kevinfodness]

Issue

When the "rollup phpcs to parent" option is selected, the .phpcs directory with the .gitkeep file is maintained, even though the configuration should be handled by the parent, and assumptions shouldn't be made about the location of the cache directory.

Steps to Reproduce

Create a new WordPress plugin and select the option to rollup phpcs configuration to the parent. Observe that the .phpcs directory still exists in the plugin folder.

Recommended Solution

Remove the .phpcs directory and its contents from the plugin if "rollup phpcs to parent" option is selected.