React to MSBuild Traversal and NoTargets SDK updates (#52895)

React to MSBuild Traversal and NoTargets SDK updates (#52895)

* Remove custom rebuild entry point in Build.proj

The rebuild target was added into the Traversal SDK here: https://github.com/microsoft/MSBuildSdks/commit/fd7660d62b139f282926d98212b7aeb3e6460daa#diff-ad560c0828c6bab536a01e43bb052bfce14a959b8df2c3f89cccfca0b399681c

* Update global.json

* Update global.json

* Update native-binplace.proj

* Update externals.csproj

* Update native-binplace.proj

* Update native-binplace.proj

* Default tfm for NoTargets projects

* Don't run GenFacades on ApiCompat.proj

* ApiCompat fix and packaging cleanup

* Fixes

* Only set if not multi-targeting