Publish RBS

[ksss]

Current

Currently, when a user does a rbs collection install, prime uses the type definition of gem_rbs_collection.
prime has a history of copying the sig directory from gem_rbs_collection (link), but does not include the sig directory in the gem package.
rbs searches for the type definition of prime in the order of gem package -> rbs repository -> gem_rbs_collection, and uses the type definition of gem_rbs_collection found last.

Change

Include the files in the sig directory in the gem package to give preference to type definitions in this repository.

Confirmation

1. Apply this change.
2. Run in this repo.

$ bundle exec rake build install

3. Add prime at Gemfile in other repo.
4. Call bundle exec rbs collection install/update in other repo.
5. Check prime in rbs_collection.lock.yaml.

- name: prime
  version: 0.1.2
  source:
    type: rubygems