PMUI actions should be disabled when errors prevent them from happening

[donnie-msft]

Details about Problem

NuGet product used (NuGet.exe | Visual Studio | MSBuild.exe | dotnet.exe): Visual Studio

Product version:

Worked before? If so, with which NuGet version: No

When a project is in some broken state (eg, failed to load), PMUI for another, valid project, should either block all actions, or even better, it should just allow actions to work for the valid project.

Repro steps and/or sample project

See Bad Project in Solution example: #10522
See Bad Package in project example: #10385