MR Review Panel: Improve review submission form layout
# Context
In the context of the wider effort to build an improved MR Review Panel as described in https://gitlab.com/groups/gitlab-org/-/epics/14651 and https://gitlab.com/gitlab-org/gitlab/-/issues/474794, this is step 1.
* Step 1: Review bar :arrow_left: this issue (https://gitlab.com/gitlab-org/gitlab/-/issues/525839)
* Step 2: New drawer to preview Review pending comments (https://gitlab.com/gitlab-org/gitlab/-/issues/525841)
* Step 3-?: Iterate on improving drawer (future issues)
This issue covers the improving of the form used to submit a review (after clicking Finish Review)
# Tasks
1. Change radio buttons and submit into 3 buttons
1. Approve
- Tooltip: "Submit feedback and approve this merge request."
3. Request changes
- Tooltip: "Submit feedback that should be addressed before merging."
5. Comment
- Tooltip: "Submit feedback without explicit approval."
1. Move delete pending comments button into the review popover
# Mockup
[Figma](https://www.figma.com/design/4KVQUkUDoZilkO4D1o1bvw/Merge-request?m=auto&node-id=12699-218892&t=sr1j2nuJokCVvOfE-1)
| Before | After (this issue) |
| ------ | ------ |
|  |  |
# Implementation plan
These changes can be shipped independently of the other issues (listed in the context section of this description). (to be confirmed by @mle)
issue