fix: prevent user-entered text with | characters from being truncated in activity feed (#8844)

Prevents a variety of user-entered texts that can contain `|` characters from being truncated in the activity feed, affecting: issue & PR titles, comment content, review comments, and review dismissal comments.

Where `action.content` was containing a pipe-separated list of UI data fields before, it now uses a JSON-encoded string array.  The old format is still supported for reading from the feed.  In some places where `action.content` was not using this format, or where user-generated text was not inserted, the old format is retained.

Fixes part of the cause behind #8781, allowing small mermaid graphs to be rendered in the feed (for now...) --
![image](/attachments/4de98825-4fb7-4b5d-87c3-bd54d6f0a1d1)

## Checklist

The [contributor guide](https://forgejo.org/docs/next/contributor/) contains information that will be helpful to first time contributors. There also are a few [conditions for merging Pull Requests in Forgejo repositories](https://codeberg.org/forgejo/governance/src/branch/main/PullRequestsAgreement.md). You are also welcome to join the [Forgejo development chatroom](https://matrix.to/#/#forgejo-development:matrix.org).

### Tests

- I added test coverage for Go changes...
  - [x] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8844
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

models/activities/action_test.go

@@ -308,14 +308,69 @@ func TestDeleteIssueActions(t *testing.T) {
 	})
 	require.NoError(t, err)
 	err = db.Insert(db.DefaultContext, &activities_model.Action{
-		OpType:  activities_model.ActionCreateIssue,
-		RepoID:  issue.RepoID,
+		OpType: activities_model.ActionCreateIssue,
+		RepoID: issue.RepoID,
+		// Older Content format...
 		Content: fmt.Sprintf("%d|content...", issue.Index),
 	})
 	require.NoError(t, err)
+	err = db.Insert(db.DefaultContext, &activities_model.Action{
+		OpType: activities_model.ActionCreateIssue,
+		RepoID: issue.RepoID,
+		// JSON-encoded Content format...
+		Content: fmt.Sprintf("[\"%d\",\"content...\"]", issue.Index),
+	})
+	require.NoError(t, err)
 
 	// assert that the actions exist, then delete them
-	unittest.AssertCount(t, &activities_model.Action{}, 2)
+	unittest.AssertCount(t, &activities_model.Action{}, 3)
 	require.NoError(t, activities_model.DeleteIssueActions(db.DefaultContext, issue.RepoID, issue.ID, issue.Index))
 	unittest.AssertCount(t, &activities_model.Action{}, 0)
 }
+
+func TestGetIssueInfos(t *testing.T) {
+	tt := []struct {
+		content string
+		field1  string
+		field2  string
+		field3  string
+	}{
+		{
+			content: "4|",
+			field1:  "4",
+		},
+		{
+			content: "2|docs: Add README w/ template sections",
+			field1:  "2",
+			field2:  "docs: Add README w/ template sections",
+		},
+		{
+			content: "2|docs: Add README w/ template sections|Some comment...",
+			field1:  "2",
+			field2:  "docs: Add README w/ template sections",
+			field3:  "Some comment...",
+		},
+		{
+			content: "[\"4\"]",
+			field1:  "4",
+		},
+		{
+			content: "[\"2\", \"docs: Add README w/ | template sections\"]",
+			field1:  "2",
+			field2:  "docs: Add README w/ | template sections",
+		},
+		{
+			content: "[\"2\", \"docs: Add README w/ | template sections\", \"Some | comment...\"]",
+			field1:  "2",
+			field2:  "docs: Add README w/ | template sections",
+			field3:  "Some | comment...",
+		},
+	}
+	for _, test := range tt {
+		action := &activities_model.Action{Content: test.content}
+		issueInfos := action.GetIssueInfos()
+		assert.Equal(t, test.field1, issueInfos[0])
+		assert.Equal(t, test.field2, issueInfos[1])
+		assert.Equal(t, test.field3, issueInfos[2])
+	}
+}