RPM Support

Refactor depsolving part 2 (necessary for bugfix)

The scope of UnitSolvableMapping needs to be reduced for reasons discussed on the PR. It makes sense to keep this separate from the bugfix to reduce noise.

re: #4962 https://pulp.plan.io/issues/4962

Refactor to remove decorator snake pit

Nested decorators 3-8 deep, sometimes with nontrivial logic inside makes it difficult to understand what's really going on inside functions. Some decorators even modify the function signature so that it is called with different arguments than the docstrings show.

Get rid of all of that. Unrolling everything made the code much easier to understand and reason about.

re: #5068 https://pulp.plan.io/issues/5068

Simplify DB loading code

.only() is better for us than .excludes()

re: #5068 https://pulp.plan.io/issues/5068

Replace the Pulp version of module dependency code with MBS version

Use Module Build Service code to create libsolv dependencies for modules. The code is better commented, cleaner, possibly less buggy and has had more eyes on it. It is otherwise almost identical. Some of the MBS implementation was stripped out as not necessary, so this code is closer to the FUS version.

re: #5068 https://pulp.plan.io/issues/5068

Address PR review feedback

Wanted to rebase but it got nasty

re: #5068 https://pulp.plan.io/issues/5068

Small refactor

Get rid of a small single-purpose function and replace with a loop. Move other single-purpose functions into their caller locations.

re: #5068 https://pulp.plan.io/issues/5068

Fix KeyError

Epoch doesn't always exist but we still have to use it.

re: #5068 https://pulp.plan.io/issues/5068

Add an "ignore_missing" parameter to the depsolver

Assist with debugging so that the solvable faking behavior can be disabled easily.

re: #5068 https://pulp.plan.io/issues/5068

Run createwhatprovides() more aggressively

This is probably more than necessary but it doesn't hurt anything and it's annoying to debug issues where it isn't done often enough.

Also reusing the solver instead of recreating it every attempt.

Also renamed the depsolving methods to have more accurate names.

re: #5068 https://pulp.plan.io/issues/5068

Refactor the Solver() handling of target repos

Libsolv only allows one repo at a time to be "installed" so we should reflect that in the API.

re: #5068 https://pulp.plan.io/issues/5068