Notification on Comment/Reply Edit

* As a user included in a comment thread
* I want to receive a notification when a comment or reply is edited
* so that I can stay informed about a request

**Assumptions & Scope**
This is to build off an AC that was missed in #3448

It appears that #3448 missed one scenario, which is sending a notification to all users in a comment thread (i.e., either an Assignee, Watcher, or a user tagged in the comment or reply in the comment thread) when a comment or reply in the thread is edited.

#3448 focused specifically when a comment or reply is edited to tag a user - but it did not cover notifications when a comment or reply is edited, and no users are added as being tagged (i.e., just a normal comment or reply being updated to add or remove information)

What is IN scope?

What is NOT in scope?

**Acceptance Criteria**

**Scenario 1: Comment/Reply Edited Notification**
* GIVEN a user is part of a comment thread on a request (as the Assignee, Watcher, or they have been tagged in the thread)
* WHEN a poster of a comment or reply in the comment thread edits their comment or reply
* AND resends their edited comment or reply
* THEN all users part of the comment thread should receive a notification of the edited comment or reply
* AND the poster of the comment or reply that was edited should not receive a notification

**Dependencies? What is the impact of this dependency? (If so, link dependency in the ticket, make it visible in a team´s backlog)**

**Validation Rules? (If yes, list here)**

**Design**
@xxx - please link the Design here

**Definition of Ready**

1. [ ] Is there a well articulated User Story?
2. [ ] Is there Acceptance Criteria that covers all scenarios (happy/sad paths)?
3. [ ] If there is a user interface, is there a design?
4. [ ] Does the user story need user research/validation?
5. [ ] Does this User Story needs stakeholder approval?
6. [ ] Design / Solution accepted by Product Owner
7. [ ] Is this user story small enough to be completed in a Sprint? Should it be split?
8. [ ] Are the dependencies known/ understood? (technical, business, regulatory/policy)
9. [ ] Has the story been estimated?

**Definition of Done**

1. [ ] Passes developer unit tests
2. [ ] Passes peer code review
3. [ ] If there's a user interface, passes UX assurance
4. [ ] Passes QA of Acceptance Criteria with verification in Dev and Test
5. [ ] Confirm Test cases built and succeeding
6. [ ] No regression test failures
7. [ ] Test coverage acceptable by Product Owner
8. [ ] Ticket ready to be merged to master or story branch
9. [ ] Developer to list Config changes/ Update documents and designs
10. [ ] Can be demoed in Sprint Review
11. [ ] Tagged as part of a Release
12. [ ] Feature flagged if required
13. [ ] Change Management activities done?

No files or tests are named. Start by reviewing issue #3448 and the existing comment/reply edit and notification flow, then identify how assignees, watchers, tagged users, and the edited poster are determined. Done means adding coverage for edited comments and replies, with notifications sent to thread participants except the editor, and all relevant tests passing.

Written by the indexing model from the issue text.