Mypy not showing errors on newly created files

[luabud]

This is when "mypy-type-checker.reportingScope" is set to "workspace"

If you create new files with errors reported by mypy, it won't report their errors until you restart the server.

Repro steps:

• Create new files with problems mypy should report
• Notice they are not reported as problems

mypynewfilelintallbug.mp4

[karthiknadig]

This is same as #88