Update ee13b5 and 1a02b0 rules to clarify that transcript for video content does not need to be visible

Closes issue(s): #2186

Updates:

Added 1.3.1 secondary requirement for both:
- Video element visual-only content has transcript (ee13b5)
- Audio and visuals of video element have transcript (1a02b0)
Removed "visible" from Expectation of both:
- Video element visual-only content has transcript (ee13b5)
- Audio and visuals of video element have transcript (1a02b0)
Added assumption as per CG decision for both:
- Video element visual-only content has transcript (ee13b5)
- Audio and visuals of video element have transcript (1a02b0)
Added non-visible transcription passed example (Passed Example 3) for both:
- Video element visual-only content has transcript (ee13b5)
- Audio and visuals of video element have transcript (1a02b0)
Tweaked a little bit the wording of other passed examples to clarify they are visible and differentiate them from the non-visible one.
Added failing example (Failed Example 3) of transcript not included in the acc tree only for "Audio and visuals of video element have transcript (1a02b0)" since the other rule already had this failure in place.

Need for Call for Review: This will require a 2 weeks Call for Review

Pull Request Etiquette

[ ] Make sure you're requesting to pull a branch (right side) to the develop branch (left side).
[ ] Make sure you do not remove the "How to Review and Approve" section in your pull request description

[ ] Add yourself (and co-authors) as "Assignees" for PR.
[ ] Add label to indicate if it's a Rule, Definition or Chore.
[ ] Link the PR to any issue it solves. This will be done automatically by referencing the issue at the top of this comment in the indicated place.
[ ] Optionally request feedback from anyone in particular by assigning them as "Reviewers".

[ ] Close any issue that the PR resolves. This will happen automatically upon merging if the PR was correctly linked to the issue, e.g. by referencing the issue at the top of this comment.

Go to the “Files changed” tab
Here you will have the option to leave comments on different lines.
Once the review is completed, find the “Review changes” button in the top right, select “Approve” (if you are really confident in the rule) or "Request changes" and click “Submit review”.
Make sure to also review the proposed Call for Review period. In case of disagreement, the longer period wins.