Improve the TypeScript lint/intellisense experience

[eemeli]

This is a follow-up to #569, where some of the dev-env challenges were discussed with @gregtatum.

With these changes, the lint task is no longer dependent on build and intellisense works immediately for internal cross-package dependencies.

The dependency of test on build remains, and it's turning out to be more difficult without in-depth changes. Briefly, Mocha does not offer an out-of-the-box path aliasing as e.g. TypeScript's paths or Jest's moduleNameMapper. This means that something like a Babel plugin would need to be registered for tests, as well as ts-node for handling the TypeScript sources. Alternatively, all of the tests could be ported to Jest and/or TypeScript. That sounds like more work than it's worth at this time.

[gregtatum]

Thanks, everything seems to be working well on my end.