This prevents name collisions for the targetRef variables

Fix name collision, reuse context within switch statement

Description

This should stop any name collisions. I'm not sure why in the tests the sourceNames are now less unique in some spots, but it should all compile just fine.

Fixes #1904

Checklist

• The existing code style is followed
• The commit message follows our guidelines
• Performed a self-review of my code
• Hard-to-understand areas of my code are commented
• The documentation is updated (as applicable)
• Unit tests are added/updated
• Integration tests are added/updated (as applicable, especially if feature/bug depends on roslyn or framework version in use)