Add support for xdebug 3

New configuration variables for xdebug 3. See the upgrade docs.
This is theoretically backwards compatible, because it defaults to using configuration for xdebug 3.
However, you will have to manually lock your xdebug version to 2.x, since this role will install the latest xdebug version for your given xdebug_php_version.

Add more xdebug.ini variables

Also removed the ability to enable the xdebug module by default, which means this role no longer needs dependencies.

Initial Release

Install and configure xdebug from the apt repositories.