Roadmap post: new build system (Rewatch)

[fhammerschmidt]

Showcase what we can do now with rewatch what was basically not possible with the old build system before.

• explain the problems with the old watcher
• compare compile times both, incremental and full of a monorepo
• what package managers with what setups are now supported (yarn, pnpm, deno, bun)?
• what is not supported and do we have an outlook what rewatch will enable in the future (embed-lang, PnP modes???)

[fhammerschmidt]

especially file-watching did never work with the old build system in monorepos.
we had to setup watchexec (https://forum.rescript-lang.org/t/include-a-module-everywhere-using-open-helper-in-bsc-flags-fail-when-compiling-helper-res/4083/2)

And this triggered a lot of recompiles as there was no fine-grained dependency tracking over packages.
So even if the API of a package did not change at all and I changed something internally only, all dependants were recompiled.