[11.3] Add support for a single inherited member

[YKWeyer]

This adds support for reading the permissions of a specific member for a group/project including inherited permissions:
https://docs.gitlab.com/ee/api/members.html#get-a-member-of-a-group-or-project-including-inherited-members

I tried to respect the naming logic already used:

	All members	Single member
Without inheritance	members	member
With inheritance	allMembers	allMember

If you think this might be confusing, i could also name it inheritedMember (although this might not be perfect either, since both regular AND inherited members will be returned)

[GrahamCampbell]

Thanks for this. Could you add some tests too?

[YKWeyer]

👍 I just added tests for the two allMember methods.

This might be caused by my setup, but make install wouldn't succeed entirely ("Couldn't find any bin namespace."), and I had to
add "phpunit/phpunit": "^9.0", in the dev requirements of composer in order to run the tests.

[GrahamCampbell]

Try running make clean && make install && make test. You may get some bin warnings, but they should be harmless.

[GrahamCampbell]

If you have custom composer config in your home directory or globally installed packages, it's possible that could have messed things up.

[GrahamCampbell]

Anyway, this looks good to me. Thanks. 🍻