No monorepo-level linting and typechecking

Individual subfolders have `lint` and `typecheck` scripts in their `package.json`, but there's none in the parent folder (https://github.com/sillsdev/EthnoLib/blob/main/package.json), nor any global linting or typechecking run in GHAs (https://github.com/sillsdev/EthnoLib/tree/main/.github/workflows).