…y and other actions

This commit implements Podcastindex-org#240 and initial support for Podcastindex-org#233.

A menu is added to comments that support initiating the following
actions:
- Reply to post - currently just navigates to the post in it is
  original system
- Copy link to post
- Open in original site - opens the post in its original system at
  another tab
- Follow author of the post - currently just navigates to the
  profile of the author on its original system

This commit is based on
nathangathright/comment-thread-mockup@6b2f716

Related issues:

- Podcastindex-org#240
- Podcastindex-org#233

Co-authored-by: Nathan Gathright <[email protected]>

This commit implements one next step to automate the remote
interactions with comments and commenters.

This uses the WebFinger protocol and API and also the
OStatus Subscribe mechanism.

There are very little guardrails, so some might need to
be implemented later (e.g. verifying the input for the
interactor account).

Known issues:
When the user is first prompted to enter their account,
the opening of a new tab for interaction will be blocked
as a pop-up.

Related issues:
- Podcastindex-org#233
- Podcastindex-org#240

Related links:
-
https://socialhub.activitypub.rocks/t/represent-endpoint-for-remote-interaction/480

…-comments

References:
-
Podcastindex-org#253 (comment)

Co-authored-by: Steven Crader <[email protected]>

References:
-
Podcastindex-org#253 (comment)

Co-authored-by: Steven Crader <[email protected]>

This commit implements the feature of closing the comment menu
when the user clicks outside of it.

It is based on a similar implementation on the class/component
TopBar.

References:
-
Podcastindex-org#253 (comment)

Co-authored-by: Steven Crader <[email protected]>