[extension/remotetap] add basic implementation of the extension

[atoulme]

This makes the implementation work in a simple setting, rendering the JSON output of the data traversing the extension via websocket with a HTML select input to pick the tap to connect to.

From this implementation, there are a number of improvements we can work towards making:

• It might make more sense for processors to register with extensions rather than having the extension define the processor endpoints. Because extensions don't have access to the processor list, you end up having to enter the processor name and endpoint in the extension config right now, which is less than ideal.
  If the processor can register with this extension, however, I'd like it to be through a shared interface other extensions can also use, so we can over time have multiple extensions register with taps. This would allow other extensions to benefit from taps.
• The extension is very, very simple - a toy implementation to allow the community to understand the remote tap mechanism and take it from there.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.