make: add capability to check config for test-with-config

[miri64]

Contribution description

This adds another dependency for test-with-config that uses (optional) check-config scripts within the tests-with-config directory to check if the config required for the test is available. If the config is not available, the make test-with-config target will fail with an appropriate error message.

Testing procedure

I will provide a config checker for tests/gnrc_dhcpv6_client as a follow-up (#16797). With that, this PR will be testable.

Issues/PRs references

None

[miri64]

Took your suggestions and added my own spin to it (and also fixed some of the wording ;-))

[kfessel]

this is also long and difficult to read -> comment to explain

[kfessel]

I am ok with your spin on the comments mine where mostly for inspiration.

I tested this with the check-config provided in PR #16797 failing and succeeding as expected ✔️

these PRs have a small problem of hen and egg

this should be squashed and
checked by murdock and tests should be run

[miri64]

checked by murdock and tests should be run

test-with-config tests are not run by murdock anyways...

[miri64]

these PRs have a small problem of hen and egg

Not really: One introduces the feature and one uses it for one specific test. There is no cyclic dependency between them, so no hen-egg-problem :-).

[kfessel]

these PRs have a small problem of hen and egg

Not really: One introduces the feature and one uses it for one specific test. There is no cyclic dependency between them, so no hen-egg-problem :-).

i got into the hen and egg while testing since i did not want to use another pr to test this of cause there is no circular dependancy graph

[kfessel]

Suggested change

	"tests is not available, check $${t#$${RIOTBASE}/} failed." \
	"tests is not available, check $${t#$${RIOTBASE}/}." \

[kfessel]

" check tests/gnrc_dhcpv6_client/tests-with-config/check-config.sh failed. "
i read the "check" a a verb and it sounded wrong to me, but if check and the filename are one noun it sounds correct

[miri64]

That looks to me like a part of the sentence is missing...

[kfessel]

i was just citing the part after the , but as said i was reading it kinda wrong

[kfessel]

I think this is good to merge.