Check the path following the prefix the right way since on Windows the path does not start with "/".
Fix view state migration issue by adjusting the file path strings handling.
Fix #6954 by migrating all "panelState" preferences if the key is a valid one.
Merge pull request #6938 from adobe/rlim/project-path-migration

Fix the project view state migration issue.
Fix PreferencesManager test.

This is a fix for #6917. The problem was that
`openAndSelectDocument(nonProjectFile` was being called outside of a `run()`
block, so sometimes the nonProjectFile would be open rather than file that
was supposed to be open.