Set Random and Test to be weak deps

[jakobnissen]

The test-related functionality is still there, but requires loading Random and Test.

Note that THIS MIGHT BE A BREAKING CHANGE, since users could call these functions without loading Test or Random previously.
However, I think we just need to make this breaking change. There is no way around it, and as we begin moving more stuff out of the sysimage, it becomes increasingly annoying that TranscodingStreams has these needless deps.

[mkitti]

Do we actually need these to be package extensions?

[jakobnissen]

You mean, whether we can just delete them functions instead? I think they're useful for downstream dependents, and it's more breaking to completely remove them.

[sjkelly]

Seems like a reasonable middle ground between deletion and hard-dep! LGTM!

[mkitti]

Overall, I think this is headed in the right direction. Let's consider it a breaking change. I bumped the minor version to reflect this.

[mkitti]

For the version change, it looks like will need to update a few packages' compat for CI to pass:
https://github.com/JuliaIO/CodecBase.jl/blob/master/Project.toml

[jakobnissen]

Can we just merge this anyway? None of these downstream packages will actually be affected by this change, since their compat will prevent them from installing version 0.10 (which is indeed why this CI fails).
I think we should also fix CI for this package such that it doesn't auto-break for new breaking releases, but that's a separate issue.

[jakobnissen]

Actually, let's remove the downstream tests from TS's tests, and add it to this repo's CI instead.

[jakobnissen]

@mkitti I believe this is ready to merge now. Should I push the button?

[KristofferC]

Looking into the PkgEval failures here JuliaLang/julia#52841 (comment), the reason for those is that this packages say that it needs both Random and Test to load the extension, but then never end up loading Random.

This used to previously work due to a bug / circumstance in that Random is in the sysimage but this behavior will be fixed with JuliaLang/julia#52841.

What can be done here and the other packages that fail are:

• Import Random in the main package.
• Add Random as a test dep and import it in runtests.jl.

cc @mkitti, @jakobnissen