One big last lock cleanup

[Jacalz]

Description:

This removes most of the unnecessary atomic types everything except for app, bindings and so on. It also fixes various small races and cleans up some code leftovers. Maps are still concurrency safe as anyone relying on goroutines might see crashes otherwise.

For #4654

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.

[Jacalz]

I backed out all changes to maps. It causes crashes for anyone updating widgets outside of the correct threads.

[andydotxyz]

Potentially seeming unrelated things, but it can be hard to know where race work leads!
But thanks for all the tidyup.