allow finding stdlibs that are normal packages in the manifest but are now stdlibs

[KristofferC]

This helps handling manifest from earlier julia versions. This is kind of the locate version of the identify fallback in #56148.

Need to write a test when this happens (and verify that this fix works).

Noted in a slack #gripes comment.

[kescobo]

Adding context from a gripe on slack that kicked this off, when I freshly cloned https://github.com/kescobo/audiommunity.org/tree/abab70896694f6ea7563fed6c460c66d892293ea and then started julia with julia --project, entering the Pkg REPL with ] immediately triggered a bunch of precompilation and throwing errors.

I was able to start julia without --project and then to ] activate ., but the user experience of being thrown into a bunch of exceptions when activating the Pkg REPL is not ideal.

[KristofferC]

This happens when we have a manifest with what is now an stdlib but in the julia version of that manifest it was not (OpenSSL).

[KristofferC]

Added test, also corrected the test from #56148 (cc @IanButterworth)

[IanButterworth]

Makes sense. So the test erroneously passed before because the projecf path was set incorrectly?

[KristofferC]

So the test erroneously passed before because the projecf path was set incorrectly?

No, that test actually worked (but it failed to test the thing it was trying to test). The change here is not fixing that, it is fixing another failure mode where we have a manifest with a package that was not an stdlib in an earlier Julia versions but now is an stdlib (e.g. OpenSSL_jl).

[KristofferC]

I tried this on the example in #60061 (comment) and it seems to work fine.