CPVM preview message should be visible at minimal verbosity

[zivkan]

Bug

Fixes: NuGet/Home#10226

Regression? no

Description

1. CPVM preview warning was changed to minimal, rather than "informational" (normal) verbosity
   • This is the same as .NET CLI's preview version warning
2. Fixed a bug in our VS logger, where minimal verbosity messages were incorrectly being treated as normal verbosity
   • Any existing LogMinimal calls would previously be hidden, and will now be written to the Package Manager output.

PR Checklist

• PR has a meaningful title

• PR has a linked issue.

• Described changes

• Tests

  • Automated tests added
    • RestoreCommand tested via modifying existing test to no longer explicitly use normal verbosity
  • AND
  • Test exception
    • VS RestoreOperationLogger not tested because there are no existing tests for it, it depends on JTF, possibly AsyncServiceProvider, and looks generally difficult to test, which doesn't seem worthwhile given the simplicity of the change made to the production code

• Documentation
  • N/A