Apply Prettier formatting

[akx]

What kind of change does this PR introduce?

• Bugfix of sorts.

Even if Prettier had technically been configured for the repo, it was never enforced, so various contributions had caused the repo to drift from Prettier style.

This PR:

• adds prettier --check to the GitHub Actions CI workflow
• adjusts the prettier settings so files in sub-subdirectories are properly formatted too, while ignoring (for the time being anyway) some files that would have made the diff here >10k lines.
• reformats files using prettier --write.

If this PR is merged, the resulting commit hash should probably be added to .git-blame-ignore-revs.

Refs #1587, 6603d6a.

Checklist:

• Unit Tests
  • Yes, in that CI now actually enforces Prettier style
• Documentation (N/A)
• Update CHANGELOG.md (N/A)
• Ready to be merged

[blikblum]

Please remove the examples folder. Prettier makes harder to understand some code there

[akx]

Please remove the examples folder. Prettier makes harder to understand some code there

Yeah, I see what you mean with the chained calls. I added a commit that peppers // prettier-ignore comments around them (as had been done with other code elsewhere).