Rework project formatting

[eritbh]

We're moving to Typescript (#761) and eslint and eslint-typescript no longer recommend using themselves as formatting tools. The TS PR #783 includes no formatting for Typescript files and we're gonna have to move our project's formatting config to something else (probably prettier, maybe dprint). This will probably involve reformatting the entire codebase under a new standard, because this repo's existing conventions are different from exosystem standards and I don't really feel like writing a whole new config for a new tool.

Any PR that reformats the project should add a .git-blame-ignore-revs file for the commit that actually applies the new formatting, and that PR should not be squash-merged to make sure that the commit referenced there maintains the correct SHA and doesn't contain non-automated changes.