Fix Rapid Diffs conflict alert link alignment and resolve locally modal padding

What does this MR do?

Fixes 2 visual issues in the Rapid Diffs conflict UI:

1. The "resolve them locally" link in the conflict alert sat lower than the "resolve conflicts on GitLab" link. It's now aligned with gl-align-text-bottom, same as the legacy diffs alert.
2. Code blocks in the "Check out, review, and resolve locally" modal had no padding. They only got padding from the copy-code wrapper, which is applied only when something changes inside #content-body. Rapid Diffs mounts this modal on document.body, so the wrapper usually never applies. The code blocks now have their own padding. The modal is shared with the merge request widget.

Screenshots

	Before	After
Conflict alert
Resolve locally modal

Reproduction steps

1. Open a merge request with conflicts and go to the Changes tab with Rapid Diffs enabled.
2. Compare the two links in the conflict alert above a conflicted file.
3. Click "resolve them locally" and look at the code blocks in the modal.