Bundle the extension with esbuild

[kddnewton]

https://code.visualstudio.com/api/working-with-extensions/bundling-extension

[kddnewton]

@xeger wanna take a shot at this? The docs look pretty clear on this, shouldn't be too bad. Seems like something worth doing (I get a warning every time I publish it that I should be doing this).

[xeger]

It wasn't a slam dunk, but I made a start at it for you. See the PR for my concerns.

I'm mildly surprised that the official Microsoft documentation has people bundling tests with tsc, and distributables with esbuild -- they must really trust both tools!

[xeger]

The PR is ready to go @kddnewton.