Improve merging issues workflow

### Problem Statement

In order to merge issues, I often must create a query which provides all the desired issues in the list, select them, and then hit merge. I often already have the pages open for two (or more) issues that I'd like to merge and do not want to have to go through this additional step of making a query to access a merge button.

I would like to merge issues quickly from the issue page, or better yet, not have to merge them in the first place.

Examples of unmerged very similar issues which we might want to do this on. Note they might get merged if you aren't looking at this right away.

These two have one frame different near the top of the trace, identical error messages:
[https://dropbox.sentry.io/issues/6944663040]()
[https://dropbox.sentry.io/issues/6944663016]()

These two are similar for most of the stack but differ at the bottom, identical error messages:
[https://dropbox.sentry.io/issues/6304034136]()
[https://dropbox.sentry.io/issues/6957059426]()

### Solution Brainstorm

1. Allow pasting a link or slug for another issue and give me a merge button.
2. Make similar issues more useful. I literally never see similar issues provide useful suggestions anymore. It's extremely often that similar issues returns no results. Any tickets with similar/identical error messages should be showing up there. Any tickets with only minor differences in stack trace, or which have identical top X number of frames should definitely be in there.
3. Improve auto-grouping to automatically merge groups of nearly identical issues. Right now we generally find this does not work very well at least in the Dropbox iOS project.

I think ideally all three of these things could improve this flow.

### Product Area

Issues