webkitgtk, wpewebkit: update to 2.40.2 and add gbm PACKAGECONFIG option
* 2.40.2 is the last stable version and it also includes security fixes.
Check:
- https://webkitgtk.org/security/WSA-2023-0004.html
- https://wpewebkit.org/security/WSA-2023-0004.html
* Add also a new entry for the gbm PACKAGECONFIG option
(enabled by default)