- mostly duplicates #25217
- update `BaselineGenerator` to produce baselines useful in 6.0 (too)
- update Baseline.Designer.props using new generator (matching 3.1.7 release)
- always suppress references expressed only in `*.nuspec` files
- needed even in servicing builds
- restore warning and errors about removed references (new for 5.0)
- adjust exclusions to handle `@(_ProjectReferenceByAssemblyName)` removal
nit: do not generate empty `<ItemGroup />` elements
* Correct `@(SuppressBaselineReference)` items
- remove out-of-date `@(SuppressBaselineReference)` items
- either 3.1.7 baselines we're using don't include reference or still using package
- fix some comments and `Condition` attributes to make remainder easy to find
- add missing `@(SuppressBaselineReference)` items
31bd4d4b1d