Add support for stopping the ESBuild service on Webpack shutdown

[Cyberboss]

Calling the new stop API mentioned in the release notes: https://github.com/evanw/esbuild/releases/tag/v0.19.11

[privatenumber]

Can you tell me more about the motivation of this change?

Few thoughts:

• In most cases, this shouldn't be necessary as the loader is loaded by Webpack to build and exit. I'm thinking it only makes sense if Webpack is loaded via Node API.
• Does this exit in Webpacks watch mode?
• Will esbuild be re-spawned if used after exit is called?
• We allow custom esbuild to be passed in. So this stop method will have to be supported there too. Maybe update implementation to accept the entire esbuild export (e.g. import * as esbuild from 'esbuild') Note this will need to be backwards compatible with just passing in transform.

[privatenumber]

I'm pulling out the esbuild upgrade here as the tests need to be updated: https://github.com/privatenumber/esbuild-loader/pull/355

[privatenumber]

Closing due to lack of activity