Derive abstract cells in top module during hierarchy

[KrystalDelusion]

What are the reasons/motivation for this change?

Previously if hierarchy had a top module then it would not derive any other abstract cells, this means that -check could miss certain kinds of errors that it would normally detect, such as in #4927.

Explain how this is achieved.

After finding (and potentially deriving) top_mod, find all of the cells included and derive them as well; similarly to how if there is no top module then all abstract modules are derived. I'm just now realising this only works for one level of abstract cells, which means we probably need some kind of recursive approach instead so I'm leaving this as draft for now. Also because it breaks under connect_rpc.

If applicable, please suggest to reviewers how they can test the change.

Includes tests/various/hierarchy_reassign_localparam.ys which fails under previous versions (instead giving the less helpful ERROR: Module name in defparam contains non-constant expressions!), but works when not using read_verilog without -defer, and/or when using hierarchy -check without -top.

[KrystalDelusion]

I seem to have found a can of worms.