Show more details about approvals in MR Summary

## Feature Description
One thing that is missing in `gitlab.nvim` and for which I frequently visit Gitlab online is a more detailed listing of approvals of a MR. In some projects we have rules like two approvals for certain files/filetypes and `gitlab.nvim` only shows `not_approved` in case there is already one approval.

I've just realized, alternatively I could use the `glab` tool for listing this from inside Neovim:
```
:!glab mr approvers

Listing merge request !454 eligible approvers:
Approval rules overwritten.
Rule "All Members" sufficient approvals (1/1 required):
Jakub Bortlík jakub.bortlik 👍

Rule "*.py" insufficient approvals (1/2 required):
Some Guy some.guy -
Jakub Bortlík jakub.bortlik 👍
```
It would be nice if this information was in some form available in the MR summary in `gitlab.nvim`.