Add bazel plugin

[Asalle]

What needs to get done

Bazel - a popular build system projects is not currently listed among available plugins.
For now you can work around it by using nil or dump plugin and call the build tool in override-build, but it is not super obvious for newbies.

Why it needs to get done

It is used to build tensorflow-lite and others

[lengau]

This is a good idea and probably applies to other crafts too (it's immediately apparent how rockcraft could benefit from this). As such, I've made an upstream request in craft-parts so the plugin can apply to all crafts: canonical/craft-parts#963