Getting ready for bzlmod

[hzeller]

It would be good to get bazel_ruloes_hdl ready for bzlmod and add a MODULE.bazel.

https://bazel.build/external/migration

The oldest currently still maintained bazel 5 (and that can only work with old-school WORKSPACE ) is on the way out at the end of the year , bazel 6 allows to have bzlmod enabled and bazel 7 enables it by default.

[MaxwellBo]

Are there any updates here? I'm finding it very painful to use this with modules and would appreciate some guidance on the correct approach to do so in the interim.