…ant (#46141)

dotnet/csharplang#3275
https://github.com/dotnet/csharplang/blob/master/meetings/2020/LDM-2020-06-24.md#interface-static-member-variance
https://github.com/dotnet/csharplang/blob/master/proposals/variance-safety-for-static-interface-members.md

Merge master into features/VarianceSafetyForStaticMembers

…rs_100

Merge 'upstream/master' into VarianceSafetyForStaticMembers

…members.

…rs_102

Remove PROTOTYPE comments from tests for variance safety with static members.

…icMembers' into VarianceSafetyForStaticMembers_103

…odeStyle layer

Fixes #47942
This is a special IDE-only analyzer that should not be exported in the CodeStyle NuGet package. We still want to retain the code in the shared analyzer layer to allow different analyzer hosts to be able to explicitly instantiate it and enforce it on command line from the CodeStyle package.

…rs_103

Merge VarianceSafetyForStaticMembers into dev16.8

Do not export IDE0079 (remove unnecessary suppressions) analyzer in C…