basic bzlmod support

[malt3]

This is the first step towards enabling bzlmod support.
On this branch, you can add the following to your .bazelrc (or add it to your bazel build flags):

.bazelrc

common --enable_bzlmod

The project should build (bazel build //...) and all tests should pass (bazel test //...).
Also, when removing the --enable_bzlmod, the project should fall back to using the WORKSPACE file and everything should still build correctly.

TODOs (maybe for future PRs):

• decide how to handle go-rpmutils: I had issues with using the replace directive in the go.mod so I forked your fork and changed the name of the module. It would be great if we either just decide to use a renamed fork or upstream the changes
• Create module extension for rpm rules (rpm rules are currently repo rules that create new repositories. This works differently under bzlmod).
• test if bazeldnf rules work in other bzlmod enabled projects
• prepare submission to BCR
• add CI tests that run tests with and without bzlmod

[msanft]

Hey @rmohr,

Could you take a look at this soon? bzlmod support would be awesome!