Fix implicit nullables

Hi @acbramley
I reviewed your MR and all the implicit nullables deprecation errors have been fixed.
There seem to be some more pipeline errors which are being fixed in #3352346 📌 Fix the issues reported by phpcs Active .
This MR can be merged.
Moving to RTBC+

Looks good

Thanks, I think the merge request should only change the nullable types compatibility, but I also see use statement changes? Is that on purpose?

Attaching stable patch file for composer patches without the use statements in the meantime.

Reverted