This PR adds the `--fields` flag to `tea pr ls` (#342), and exposes more fields specific to the `PullRequest` type:
```
--fields value, -f value Comma-separated list of fields to print.
Available values:
index,state,author,author-id,url,title,body,mergeable,base,base-commit,head,diff,patch,created,updated,deadline,assignees,milestone,labels,comments
(default: "index,title,state,author,milestone,updated,labels")
```
Co-authored-by: justusbunsi <61625851+justusbunsi@users.noreply.github.com>
Co-authored-by: Norwin <git@nroo.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/415
Reviewed-by: Norwin <noerw@noreply.gitea.io>
Reviewed-by: techknowlogick <techknowlogick@gitea.io>
Reviewed-by: 6543 <6543@obermui.de>
Co-authored-by: justusbunsi <justusbunsi@noreply.gitea.io>
Co-committed-by: justusbunsi <justusbunsi@noreply.gitea.io>