Allow sharing tabs also using hash

[lukashornych]

Some queries are so long that even after compression the generated URL with shared tab is too long for browsers. We want to provide alternative way of sharing tabs: copy hash and paste it into running lab that will open new tab in a running session.

1. in Share tab dialog, new button will appear that will copy only the hash without prefix URL
2. Share tab dialog should automatically detect too long final URL and don't allow copying URL in that case with explanation
3. in tabs row at the and, new plus button will be added, after clicking it will open context menu with Open shared tab
4. Open shared tab will open new dialog where a user will paste the copied hash or URL (the hash will be parsed from the URL) and after confirming, the rest of the logic will be same as if a shared tab URL is used

• take inspiration in Shared tab dialog for warnings