Intelligently suggest test file globs based on what's on disk

Right now, the interactive `typestat` CLI has a hardcoded list of common suggested _"where are your test files"_ globs. `test/**/*.{ts,tsx}` and the like are commonly used by projects, but there are a few places that it could probably infer them from:

* `jest.config.js` or some other common Jest location
* Equivalents to `jest.config.js` for other test frameworks
* `tsconfig.test.json`/`test/tsconfig.json` or some other common test project

It'd be nifty if the CLI looked for these on disk and added whatever already exists to the list of suggested globs.