Standard: When building 2.2 packages, put assets in netstandard2.2 TFM

[dagood]

Helps resolve https://github.com/dotnet/core-setup/issues/7567 in the best way.

Currently the NETStandard.Library 2.2 packages has assets in build/netstandard2.1/ref/. (Similar in the transport package.) Core-Setup carries this along when producing NETStandard.Library.Ref.

[wtgodbe]

CC @terrajobst

We don't have plans yet to declare a NetStandard 2.2 - the change in the package version was just to differentiate it from what 3.0 is producing. NetStandard isn't following the same timeline as the rest of dotnet core, which leaves it in situations like this where what we're producing doesn't necessarily line up with our package version scheme

[dagood]

Closing, then, since there's no concrete plan to do it--feel free to reopen if it's useful to track, but it sounds like this would be a trivial part of a larger decision/effort.

[nguerrera]

There is no TFM smaller than 2.2 that could come out of this branch. The final surface area for 2.1 comes from an earlier branch. I think you should bump the TFM now or else what does it even mean to produce things out of master?

[terrajobst]

I agree. Let's bump the TFM of master to 2.2. Worst case, we change our mind later and ship an even higher version. But it's the smallest increment that wouldn't break 2.1 customers.

[dagood]

(I missed that it was already reopened, sorry about that.)

[terrajobst]

I was about to say, wow, that's some strong leadership from @dagood :-)