[main] Onboard runtime-portable and runtime

[lbussell]

Needs two patches. I have not submitted a backport PR yet because I would like to get both runtime-portable and runtime working, and submit one PR for both. I'm submitting this now to run it through CI as a sanity check.

[lbussell]

Status: the current runtime commit in installer contains my changes, so I will update this PR to remove the unnecessary patch. dotnet/runtime#67771 has just been merged, so once it flows in, runtime will require no patches and I will update this and request review.

Update 5/11: still waiting, current commit is https://github.com/dotnet/runtime/blob/3e5517beb897faf4592d23f036446561da1e5c23/Directory.Build.props#L56

[MichaelSimons]

@lbussell - I think we should consider checking in a patch for the backported fix so that we can unblock other work. We need to update previous source build and it would be nice to have the runtime packages in it to avoid introducing a tremendous amount of prebuilts. What do you think?

[lbussell]

I think we should consider checking in a patch for the backported fix so that we can unblock other work.

@MichaelSimons I think this is a good idea, I will work on it.