Add support for `Cosim` mixin on any `Module` instead of just `ExternalSystemVerilogModule`

### Motivation

Currently, `Cosim` is defined as `mixin Cosim on ExternalSystemVerilogModule`. It should be posisble to add a `Cosim` mixin on *any* `Module`, rather than just `ExternalSystemVerilogModule`. This opens the door to inheriting from `Module` (or some other base class that extends `Module`) and still use the `Cosim` mixin. For example, if there's a ROHD version and a SystemVerilog version of the same design, it would make sense to have a base-class with port definitions, etc. and reuse it for both the ROHD and Cosim versions.

### Desired solution

Make `Cosim on Module`, and whatever other changes are needed to support it.

### Alternatives considered

_No response_

### Additional details

_No response_