Spec all constants/classes/methods in msf/core/module.rb

MSP-11496

In preparation for breaking up `lib/msf/core/module.rb` to lower its line count, spec all the classes/constants/methods reachable so that they can't be lost during the moves.  Methods are only specced by using respond_to since that's all that's necessary to detect deletion without insertion during the moves.

# Verification Steps

## specs
- [ ] `rake spec`
- [ ] VERIFY no failures