Idea: long-lived compiler server that keeps state in-memory, makes subsequent `ts-node` invocations faster with typechecking

[cspotcode]

I've had this idea kicking around for ts-node to launch its own long-lived server process, then multiple ts-node processes / threads / etc can request transpiled code and diagnostics from it.

For non-typechecking situations, swc is still simpler and faster. But if you really want typechecking and want to launch many ts-node processes, then we can auto-launch this server and connect many ts-node processes to it. So if no code has changed, then your ts-node process can start, log diagnostics, and start running code pretty quickly.

It's a wild idea, might never happen. I've labelled it "research" accordingly.