Added an option to fetch issues from gitlab. Made the file fetching a… (#2335)

* Added an option to fetch issues from gitlab. Made the file fetching asynchornous to improve performance. #2334

* Fixed a typo in loadGitlabRepo.

* Convert issues to markdown.

* Fixed an issue with time estimate field names in issueToMarkdown.

* handle rate limits more gracefully + update checkbox to toggle switch

* lint

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Co-authored-by: Timothy Carambat <rambat1010@gmail.com>
Co-authored-by: shatfield4 <seanhatfield5@gmail.com>