fix: drop strict url comparison on syncing tab

[Semro]

will resolve:

• https://github.com/Semro/syncwatch/issues/47
• some part of https://github.com/Semro/syncwatch/issues/6

subtasks:

• [x] keep tab in sync after reconnection
• [x] determine if user puts other url in tab then stop sync it
• [x] if other user in the room shares other url differ from inital then stop syncing tab
• [x] fix tests
• [x] add tests
  • [x] on page reload, should still sync tab
  • [x] on new url in the tab should not sync
  • [x] on clicking "disconnect" and then "connect" in popup should still sync tab
• [x] manual testing
  • [x] Firefox
  • [x] Firefox Android