Improve the issue_comment workflow trigger event (#29277)

Fix #29175
Replace #29207

This PR makes some improvements to the `issue_comment` workflow trigger
event.

1. Fix the bug that pull requests cannot trigger `issue_comment`
workflows
2. Previously the `issue_comment` event only supported the `created`
activity type. This PR adds support for the missing `edited` and
`deleted` activity types.
3. Some events (including `issue_comment`, `issues`, etc. ) only trigger
workflows that belong to the workflow file on the default branch. This
PR introduces the `IsDefaultBranchWorkflow` function to check for these
events.

(cherry picked from commit a4fe1cdf38f9a063e44b197ef07e4260f731c919)

Conflicts:
	modules/actions/github.go
	context

modules/actions/github_test.go

@@ -103,6 +103,12 @@ func TestCanGithubEventMatch(t *testing.T) {
 			webhook_module.HookEventCreate,
 			true,
 		},
+		{
+			"create pull request comment",
+			GithubEventIssueComment,
+			webhook_module.HookEventPullRequestComment,
+			true,
+		},
 	}
 
 	for _, tc := range testCases {