feat(editors): format all

[erickzhao]

A few changes in this PR:

• All types-only imports changed from import to import type.
• In order to align closer to the minimal-repro code formatting, I've wired up custom language formatters in main.ts where we first import Monaco. Unfortunately, the space before parens in function definitions is completely incompatible with Prettier, so we'll never get a perfectly clean unless we install StandardJS in the repo.
• tabSize: 2 and insertSpaces: true are added upon editor instantiation (fixes CSS having 4-sized tabs by default).
• Added a new Format All context menu option so that we can format all editors at once.

Future improvements:

• Control context menus via IPC from the renderer so we don't show Monaco menu items in other editable UI elements (ref [Feature Request]: Different contextMenu options depending on element right-clicked electron#35632 (comment)).
• Either format minimal-repro via Prettier or add StandardJS to this repo for consistent formatting.
• Add "Format on Save" or "Format on Publish" options to make published gists prettier. :)

[coveralls]

coverage: 79.601% (-0.6%) from 80.234%
when pulling 91f9df3 on prettier-format
into 5e6b637 on main.

[erikian]

aside: do we care about doing import type for non-Monaco types as well? If so, it might be worth using @typescript-eslint/consistent-type-imports to automatically enforce this rule for all type imports (that would probably belong in a separate PR, though).

[erickzhao]

Yeah, I think it might be a good thing to add as a follow-up. IMO it makes it cleaner to separate the types-only imports vs. code imports.