* More liberal .gitignores on TS output directories
* Use project references for Typescript projects
* Use /dist dir for Cloud Functions deployment payload
* Disable `next build` typechecking
* Fiddle with GitHub tsc jobs
* Add tsconfig.json for common
* Prefer `const` over `let` over `var`
* Kill dead code
* Fix some trivial Typescript issues
* Turn on Typescript linting in common except for no-explicit-any
* Correctly specify tsconfig dir name in functions eslintrc