Fix mypy errors

[sanders41]

Closes #1148

Code Changes

• [x] Removed __init__.py from the src dir
• [x] Removed the global ignore_missing_imports = true and moved needed ignores to the override section
• [x] Fixed mypy errors

Steps to Confirm

• [ ] Run mypy
• [ ] Run test suite

Pre-Merge Checklist

• [x] All CI Pipelines Succeeded
• Documentation Updated:
  • [ ] documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
  • [ ] documentation issue created (tag docs-team to complete issue separately)
• [ ] Issue Requirements are Met
• [ ] Relevant Follow-Up Issues Created
• [ ] Update CHANGELOG.md

Description Of Changes

Write some things here about the changes and any potential caveats

[sanders41]

@PSalant726 and @adamsachs I closed the original PR and reopened here to clean up the history

[ThomasLaPiana]

I think this is looking good now, going to give it another thorough pass

[ThomasLaPiana]

@sanders41 this looks good to me, do you want me to force merge as an admin if you aren't?

[sanders41]

Yes, that would be good. It won't let me.