UserRepository handles updating db settings better.

Moved the plex_userid to settings to expanded with functions for
updating and fetching settings, each with its own helper function
towards the database.
Since we had a linkPlexUserId function and we dont want plex_userid to
be updated from the updatesettings function we moved unlinking to a
separate endpoint and class function.
Also a new controller and endpoints for getting and updating settings.

seasoned_api/src/webserver/middleware/mustHaveAccountLinkedToPlex.js

@@ -7,10 +7,10 @@ const mustHaveAccountLinkedToPlex = (req, res, next) => {
    if (loggedInUser === undefined) {
       return res.status(401).send({
          success: false,
-         message: 'You must be logged in.',
+         message: 'You must have your account linked to a plex account.',
       });
    } else {
-      database.get(`SELECT plex_userid FROM user WHERE user_name IS ?`, loggedInUser.username)
+      database.get(`SELECT plex_userid FROM settings WHERE user_name IS ?`, loggedInUser.username)
       .then(row => {
          const plex_userid = row.plex_userid;