Introduce the GroupRule concept

This object is intended to be a signifier for a grouping of dependencies.

Merge with group rule

common/lib/dependabot/group_rule.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Dependabot
+  class GroupRule
+    attr_reader :name
+
+    def initialize(name)
+      @name = name
+    end
+  end
+end

common/spec/dependabot/group_rule_spec.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require "dependabot/group_rule"
+
+RSpec.describe Dependabot::GroupRule do
+  describe "#name" do
+    it "returns the name" do
+      my_group_rule_name = "Darren from work"
+      group_rule = described_class.new(my_group_rule_name)
+
+      expect(group_rule.name).to eq(my_group_rule_name)
+    end
+  end
+end