Streamline updating of .NET library versions in Roslyn build system

When Rosyln was updated with the version 9 .NET Library packages* it took seven weeks to get a functional insertion into Visual Studio. The majority of the work was in three areas:
- Manually adding new dependencies
- Debugging an issue where the wrong platform (browser) of an assembly had been added
- Debugging an issue with a bad crossgen assembly because different versions of the same assembly had been added as crossgen references

\* The .NET Library packages are the System.* and Microsoft.Extensions.* packages, sometimes referred to as the BCL update

These specific manual errors might not happen again, but they demonstrate that the manual update process is fragile and that errors can be expensive to diagnose.

These changes were made in PR #76890

**Expected Behavior**:
The expected behavior is that is should only take a day or two to create a new insertion of Roslyn with updated .NET library versions.

**Actual Behavior**:
The actual behavior was that it took seven weeks to get a working insertion.