Various GitHub Onebox improvements (#13163)

* FIX: Improve GitHub folder regexp in Onebox

It used to match any GitHub URL that was not matched by the other GitHub
Oneboxes and it did not do a good job at handling those. With this
change, the generic Onebox will handle the remaining URLs.

* FEATURE: Add Onebox for GitHub Actions

* FEATURE: Add Onebox for PR check runs

* FIX: Remove image from GitHub folder Oneboxes

It is a generic, auto-generated image which does not provide any value.

* DEV: Add tests

* FIX: Strip HTML comments from PR body

spec/lib/onebox/engine/github_actions_onebox_spec.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+describe Onebox::Engine::GithubActionsOnebox do
+  describe "PR check run" do
+    before do
+      @link = "https://github.com/discourse/discourse/pull/13128/checks?check_run_id=2660861130"
+
+      stub_request(:get, "https://api.github.com/repos/discourse/discourse/pulls/13128")
+        .to_return(status: 200, body: onebox_response("githubactions_pr"))
+
+      stub_request(:get, "https://api.github.com/repos/discourse/discourse/check-runs/2660861130")
+        .to_return(status: 200, body: onebox_response("githubactions_pr_run"))
+    end
+
+    include_context "engines"
+    it_behaves_like "an engine"
+
+    describe "#to_html" do
+      it "includes status" do
+        expect(html).to include("success")
+      end
+
+      it "includes title" do
+        expect(html).to include("simplify post and topic deletion language")
+      end
+    end
+  end
+
+  describe "GitHub Actions run" do
+    before do
+      @link = "https://github.com/discourse/discourse/actions/runs/873214216"
+
+      stub_request(:get, "https://api.github.com/repos/discourse/discourse/actions/runs/873214216")
+        .to_return(status: 200, body: onebox_response("githubactions_actions_run"))
+    end
+
+    include_context "engines"
+    it_behaves_like "an engine"
+
+    describe "#to_html" do
+      it "includes status" do
+        expect(html).to include("success")
+      end
+
+      it "includes title" do
+        expect(html).to include("Remove deleted_by_author key")
+      end
+
+      it "includes action name" do
+        expect(html).to include("Linting")
+      end
+    end
+  end
+end

spec/lib/onebox/engine/github_pullrequest_onebox_spec.rb

@@ -46,8 +46,9 @@ describe Onebox::Engine::GithubPullRequestOnebox do
       expect(html).to include("1")
     end
 
-    it "includes the body" do
+    it "includes the body without comments" do
       expect(html).to include("http://meta.discourse.org/t/audio-html5-tag/8168")
+      expect(html).not_to include("test comment")
     end
   end
 end