feat: add support for modules

[TendTo]

This is a first draft to add support for the new Module system that is becoming the standard for bazel.
It seems to pass all the tests at least on my machine, but I haven't really tested on different architectures yet.

Doubts

• will renovate be able to update the dependencies in this form?
• should the repo names remain unchanged or should they be dropped for the new, slimmer, module names?
  e. g. com_github_facebook_zstd -> zstd
  • This also concerns this package, that could go from com_github_nelhage_rules_boost to rules_boost
• is support for different boost versions is something you want in your package?

[ closes #482 ]

[finn-ball]

How does this significantly differ from this earlier PR?

#553

I think the main thing it adds is a module rule to select the boost version. Is that right?

[TendTo]

It's been a while since I created this pr, and it was because I needed this module version for one of my projects and the other PR was lacking some features I needed.

Mainly the boost version selection, as you noticed, and the ability to force only static boost compilation.
This latter option is not in the pr, but in another branch of the fork, since I'm not sure it is the right way to do things but I worked pretty well for me.

I think that the version selection feature can be easily implemented in the other pr, before or after the merge.

[finn-ball]

It would be nice to get this project ported over. It's fairly popular and I have a downstream PR which could depend on a port in rules_ros.

[TendTo]

Feel free to close this pr. When you merge the other one I can open another one to add the feature.
Or @finn-ball may want to add it now.

[Vertexwahn]

Thanks for your contribution!

Moving to Bzlmod was finally performed in #553

If we should overtalk something from this PR pleas open a new PR!