Introduce events for extending Theme configuration.

UX/UI Improvements

• Minor improvements to the markup tags settings page

API Changes

• Added the session.same_site configuration option
• Added ability to use a method to return the available colors for a ColorPicker FormWidget
• Added cms.theme.extendConfig & cms.theme.extendFormConfig events

Bug Fixes

• Trigger an update to the theme log even when just the filename is changed

Translation Improvements

• Added Catalan (ca) translation
• Added to the Hungarian translation