Migrations test fixes

[damyanpetev]

This should resolve the migration test flickers:

1. Several of the base tests didn't run - due to unit test tree handling patching workspace architect options that weren't there and thus the 'build of undefined' errors. NB Something off here, these should've failed permanently instead of occasionally when running first in order, so there might be an issue w/ resetting the test tree still.
2. The single NG LS test would fail if it didn't run first in order or a prior test would properly add a component.ts file of the same path and load it correctly. Turns out the ng LS also needs addMissingFileRoot to consider/compile the new component.ts since we scan the html file first.

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them