[WIP] Explore plugin configs

- RuboCop config requires only the RuboCop plugins whose gemspec is loaded
- Each plugin has a corresponding file of defaults which are inherited
- Labels are attached automatically to PRs touching each config file

TBD:
- Should we have a minimal config? Should we keep the existing config as
  is, and instead add an "everything.yml" config?
- Should we test compatibility with _just_ RuboCop and no plugins?
- What cops to enable? Maybe disallowing "pending" shouldn't apply to
  plugins, so we don't break consumers?

.github/labeler.yml

@@ -1 +1,8 @@
-"config change": rubocop.yml
+"config change": rubocop*.yml
+"hq": rubocop.yml
+"graphql": rubocop.graphql.yml
+"minitest": rubocop.minitest.yml
+"performance": rubocop.performance.yml
+"rails": rubocop.rails.yml
+"rake": rubocop.rake.yml
+"rspec": rubocop.rspec.yml

Gemfile

@@ -8,3 +8,12 @@ gem "diffy"
 gem "minitest"
 gem "pry-byebug"
 gem "rake"
+
+group :plugins do
+  gem "rubocop-graphql"
+  gem "rubocop-minitest"
+  gem "rubocop-performance"
+  gem "rubocop-rails"
+  gem "rubocop-rake"
+  gem "rubocop-rspec"
+end

Gemfile.lock

@@ -7,10 +7,18 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
+    activesupport (7.0.4.2)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (>= 1.6, < 2)
+      minitest (>= 5.1)
+      tzinfo (~> 2.0)
     ast (2.4.2)
     byebug (11.1.3)
     coderay (1.1.3)
+    concurrent-ruby (1.2.0)
     diffy (3.4.2)
+    i18n (1.12.0)
+      concurrent-ruby (~> 1.0)
     json (2.6.3)
     method_source (1.0.0)
     minitest (5.17.0)
@@ -23,6 +31,7 @@ GEM
     pry-byebug (3.10.1)
       byebug (~> 11.0)
       pry (>= 0.13, < 0.15)
+    rack (3.0.4.1)
     rainbow (3.1.1)
     rake (13.0.6)
     regexp_parser (2.6.2)
@@ -39,7 +48,27 @@ GEM
       unicode-display_width (>= 2.4.0, < 3.0)
     rubocop-ast (1.24.1)
       parser (>= 3.1.1.0)
+    rubocop-capybara (2.17.0)
+      rubocop (~> 1.41)
+    rubocop-graphql (0.19.0)
+      rubocop (>= 0.87, < 2)
+    rubocop-minitest (0.27.0)
+      rubocop (>= 0.90, < 2.0)
+    rubocop-performance (1.16.0)
+      rubocop (>= 1.7.0, < 2.0)
+      rubocop-ast (>= 0.4.0)
+    rubocop-rails (2.17.4)
+      activesupport (>= 4.2.0)
+      rack (>= 1.1)
+      rubocop (>= 1.33.0, < 2.0)
+    rubocop-rake (0.6.0)
+      rubocop (~> 1.0)
+    rubocop-rspec (2.18.1)
+      rubocop (~> 1.33)
+      rubocop-capybara (~> 2.17)
     ruby-progressbar (1.11.0)
+    tzinfo (2.0.6)
+      concurrent-ruby (~> 1.0)
     unicode-display_width (2.4.2)
 
 PLATFORMS
@@ -50,6 +79,12 @@ DEPENDENCIES
   minitest
   pry-byebug
   rake
+  rubocop-graphql
+  rubocop-minitest
+  rubocop-performance
+  rubocop-rails
+  rubocop-rake
+  rubocop-rspec
   rubocop-shopify!
 
 BUNDLED WITH

rubocop.minitest.yml

@@ -0,0 +1,2 @@
+Minitest:
+  Enabled: true

rubocop.yml

@@ -3,6 +3,22 @@ inherit_mode:
   - Exclude
   - Include
 
+<%
+  # Identify installed RuboCop plugins to configure
+  plugin_configs = {
+    "rubocop-graphql" => "rubocop.graphql.yml",
+    "rubocop-minitest" => "rubocop.minitest.yml",
+    "rubocop-performance" => "rubocop.performance.yml",
+    "rubocop-rails" => "rubocop.rails.yml",
+    "rubocop-rake" => "rubocop.graphql.yml",
+    "rubocop-rspec" => "rubocop.rspec.yml",
+  }.select { |plugin_name, _| Gem.loaded_specs.include?(plugin_name) }
+%>
+
+require: <%= plugin_configs.keys.to_json %>
+
+inherit_from: <%= plugin_configs.values.to_json %>
+
 AllCops:
   StyleGuideBaseURL: https://shopify.github.io/ruby-style-guide/