Marking extensions as optional

[MauricioFauth]

Feature Request

Q	A
New Feature	yes
RFC	yes
BC Break	no

Summary

It would be great to have a way to mark extensions as optional, to be able to test with the extensions and without the extensions.
This way is possible to test if the code works correctly when the optional extension is not installed.

Maybe a new configuration key like optional_extensions.

• Related to Add support for PHP 8.3 laminas-serializer#49

[boesing]

My 2cents here

We should just continue even tho extensions could not get installed.
Let composer install handle the missing extensions instead, that should also handle the "optional" extensions as expected.