Use private notes as tags next to users' names

**Is your feature request related to a problem? Please describe.**
Not a problem, but an inconvenience?

Mastodon allows users to write notes on other users' profiles, server-side. Currently Phanpy supports viewing the note with a nice thematic style on the user's profile. It works well. However, they do not show up elsewhere, so one has to actively open a user's profile to see the notes.

**Describe the solution you'd like**
Similarly to how it worked with the Reddit Enhancement Suite (RES) extension, it would be great if the user notes could show up as tags next to users' usernames anywhere on the Phanpy interface (with the exception of the profile view, to avoid redundancy).

I can see a couple of issues:

* In the RES extension, the tags were client-side, so it was easy to fetch them when a user was displayed. I do not know how much it would add to server load to fetch the private notes of the displayed users, especially when one considers multi-column layouts and such.
* Private notes can be long or multi-line, therefore Phanpy could establish a format for only the first line of the private note to be considered as a user tag. Something like `phanpy-tag: friendly user` is then displayed as `friendly user`.

**Describe alternatives you've considered**
Well, I suppose it could be cached locally after manually viewing each profile, if live fetching notes of displayed users is not possible.

**Additional context**
I don't think there's more to add, but I will if requested.