Fix issues resolving the issue title in Gitlab

Major modernization release.

What's new
• Works again on modern GitHub (React-based issue and PR viewer) and GitLab (work items / merge requests).
• GitLab work-item drawer supported — open an item from the /-/work_items list and the timer attaches to the drawer.
• Toolbar icon opens the Harvest timer from any tab. Prefills with the current issue / PR / MR when on a supported page,
or shows a generic timer anywhere else.
• Firefox support.
• Matches the site theme (light or dark).
• Redesigned options page.
• New logo and icon.

What's fixed
• MR pages with a collapsed sidebar no longer hide the widget.
• SPA navigation between issues re-injects the widget.
• Widget size matches its state — icon-sized when closed, timer-sized when open.

See the full changelog in the repo: https://github.com/andyg5000/gitlab-harvest/blob/master/CHANGELOG.md

Fixes https://gitlab.com/blueoakinteractive/gitlab-harvest/-/issues/24

- Use og:title for more accurate title

- Fixes issues with firefox cookie access by opening widget in an iframe (https://gitlab.com/blueoakinteractive/gitlab-harvest/-/issues/23)
- Fixes issues with gitlabs new release (https://gitlab.com/blueoakinteractive/gitlab-harvest/-/issues/22)
- General code cleanup

Fixes https://gitlab.com/blueoakinteractive/gitlab-harvest/-/issues/19

Fix last issue related to support for older self-hosted gitlab instances

Fix regression with self-hosted gitlab instances that are still using the old search box selector

Fix broken extension in Gitlab due to changes in new version of gitlab. https://gitlab.com/blueoakinteractive/gitlab-harvest/-/issues/17 (https://gitlab.com/blueoakinteractive/gitlab-harvest/-/commit/a8332c442733794c1d346b747ff29325a4bf6e8c)

Replace the '/-/' in gitlab urls to make them consistent with github

Includes a layout fix for Github (https://gitlab.com/blueoakinteractive/gitlab-harvest/issues/13)

Fixed CSP to pass Firefox validation.
Added support for Gitlab Sub-Groups