Add NetFramework Configurations to OOB packages

[joperezr]

Fixes #36840

cc: @ericstj @Anipik

FYI: @maryamariyan since you are working on changes on Microsoft.Extensions that might conflict with this.
FYI: @GrabYourPitchforks since I'm changing some .cs files on Utf8String

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[ericstj]

Would it make sense to just stop binplacing NETStandardLibrary.NETFramework into RefPath completely? That's only there to support loading/running .NETStandard assemblies on .NETCore, and with this change don't we aim to eliminate all the cases where we would need to do that?

[ericstj]

Or maybe this is just another opportunity for @ViktorHofer to clean up in his PR that eliminates the RefPath for netfx.

[joperezr]

I'm pretty sure I tried doing exactly this on release 3.1 branch when I tried to fix this error initially and found many build breaks because of it, and I tried working through the errors but gave up since it felt like peeling an onion and I found the workaround for using AssemblySearchPaths instead. I'm happy to try this again if you want me to but I feel that the real time to fix this w ould be whenever we actually remove RefPath for netfx.

[ericstj]

I just don’t like this cruft in all our projects that area owners won’t understand. Let’s make sure it gets cleaned up.

[ericstj]

Functionally this looks ok. I’d like to clean up these projects before GA

[joperezr]

Do not review last change, I only made it so that we can run some CI check on allConfigurations and netfx legs given that there is a current backup on the Windows machine pools. Last change I made is temporarily changing allConfigurations and netfx to hosted pool as recommended by @safern, and once both checks pass I will revert that last yml change and merge this.

[joperezr]

Green CI on netfx and allConfigurations leg 😄

Here is the link to the build for future reference: https://dev.azure.com/dnceng/public/_build/results?buildId=730238&view=results

I'll now undo last commit that made this temporary change and merge the PR. Thanks @ericstj and @safern for the review, I'll follow up and clean up the way we build implementations against targeting packs.

[ViktorHofer]

@joperezr please wait with addressing the follow-up feedback until #35606 is in as it overlaps.