Have a Bazel-based setup for the tool

[rockbruno]

Instead of having to setup everything manually, in practice we should have a rule akin to rules_xcodeproj that wires up as many things as possible on behalf of the user.

[maxwellE]

Does it make sense for us to keep our current SPM setup or should we move the configuration to Bazel native? Do we want to use rules swift package manager?

[rockbruno]

At a glance I guess we would need the two things: The tool code itself (which could be either, I like SPM for its simplicity but we could use Bazel too if it doesn't make the setup a lot more complex), and then some sort of rules_sourcekitbsp native bazel logic that has the auto setup bits. It might be the case that putting everything in bazel would make this easier to setup, I guess we have to try and see what happens

[maxwellE]

Getting this started here #45