Test Endpoint

[motorina0]

Summary

• nostrclient extension is being used by nostrmarket extension
• some users complain that their events do not get published to relays
• it is hard to tell if the issue is caused by the nostrmarket extension or by nostrclient

This PR adds an easy to use UI that allows regular users to test if their nostrclient extension works as expected. If yes, then the problem lies in nostrmarket (or any other extension that might use nostrclient)

All the user has to do is

• enter its public key (hex or npub)
• write a message
• send the message
• check in a chatting app (like Iris) that the message is received
• send a message from the chatting app
• check in nostrclient that the event is received (note the content is not decypted)

https://user-images.githubusercontent.com/2951406/236446128-fe18b50a-4686-48a2-9eca-0883acb2dab4.mov

[callebtc]

Replaced button with expansion item and added "copy URL" button.