[BUGFIX] Respect 'excludePattern' with static brushes setup

The 'excludePattern' from the BrushDiscovery configuration must be evaluated in
static brushes context too. This fix introduces brush identifier intersection with the 
underlying discovery configuration when using static brushes.
[BUGFIX] Fixing API changes in ContentElement / Flexform DO

The API changed in a minor release. This fix re-introduces the necessary controller
template variable assignment `flexform` + the missing `language` getter to make
the template Content/Render from version 2.0 working again. All changes were marked
as deprecated and removal for version 3.0 of ext:beautyofcode.
[FIX] Updating .gitignore for JetBRAINS PhpStorm metadata directory exclusion