Gitlab merge requests utils by Vitaliy Pavliyk

# NEW
## "NEW COMMITS" and "NEW COMMENTS" badges
Now, extension will remember number of commits and comments when you approve merge request. If the merge requests has new commits or new comments since your approval, a new badge will appear on the merge request card. You will need to acknowledge changed by revoking approval and approving merge request again to clear NEW X badges

## Merge requests count in columns headers in Kanban board mode
Now, kanban columns contain a number of merge requests located in this column.
*Note: merge requests list is limited by merge requests located on the current original page, so the number displays only merge requests on the current page*

## Replace native discussions badge and add icon to number of user's threads
Native GitLab discussions badge is replaced by custom once with total number of threads (closed/total) and number of user's threads (closed/total). The feature was introduced in v1.0.0, but now an icon to user's threads badge is added for supposedly easier recognition

# FIX
- Adapt parsing to new GitLab version
- Make the Kanban board mode not work on merge requests tabs other than "Open" ("Merged", "Closed" and "All" tabs will be displayed in List mode)
- Fetch full discussions list by using paginated requests so the discussions number is displayed correctly on the merge request

# Known issues
Currently, due to GitLab's new approach of asynchronous merge requests loading, the extension will work incorrectly and will interfere with merge requests displaying while navigating through tabs "Open", "Merged", "Closed" and "All" and also while navigating through merge requests paginated pages. To display the page correctly you will need to refresh the page after navigation
This issues will be fixed soon in the next patch version