* Plugin callsigns, filechangehandler thread bug fix, plugin file perms

- Plugins are now assigned a callsign (a random string), which they use for all internal identification, like resource fetching and method calls. This is to ensure that plugins only access their own resources and methods.
- Made FileChangeHandler send off events to a queue, that is then consumed by the Loader, instead of calling import_plugin on its own, since that caused weird issues with the event loop and the thread watchdog is using.
- Plugins are now owned by root and have read-only permissions. This is handled automatically.

* Improved general look and feel of plugin tab

* Make all plugin entries have the same padding between them

* Make "No plugins installed" text look the same as "No new notifications"

Co-authored-by: WerWolv <werwolv98@gmail.com>

* root plugins

plugins can now specify if they want their methods to be ran as root. this is done via the multiprocess module. method calls are delegated to a separate process that is then down-privileged by default to user 1000, so the loader can safely be ran as root

except it isn't really safe because the plugin is imported as root anyway

* working implementation

- follows the new plugin format with the plugin.json file
- plugins are loaded in their own isolated process along with their own event loop and unix socket server for calling methods
- private methods are now prepended with _ instead of __

* converted format to f-strings