Tabs for multiple open tokens

[fredsted]

Idea: Add a tab for each open webhook URL/token, so you can quickly navigate between then.

Have a plus (+) button next to the tabs to make a new URL, so we can remove it from the top navbar.

Also an X button on the tab to delete the URL/token.

Maybe double click on the tab to rename the URL's title.

Show the amount of total requests, or maybe new "unread" requests with red (like Apple notifications counts on icons)

The open tabs, their order and state should be remembered with localStorage.