* ipc: use vql for uint types
On the plane I was reverse-engineering ipc.ts to implement it in Rust
and see if we could have a "service mode" for the CLI that we could
interact with like any other vscode process.
In doing so, I noticed that numbers in the protocol--which are used at
least twice in the message header and ID--were encoded as JSON. I was
curious what benefits we'd get from encoding them as variable-length
integers instead.
It makes the message shorter, as expected. Encode/decode time are very,
very slightly lower. I'm not sure it's worth the extra complexity, but
I have included it here for your consideration.
* fixup tests
