auth: slight refactor, setup user auth

user-auth.go contains slightly adjusted versions of auth.go functions,
for authorizing jellyfin users (admin or not). Refactored auth.go so that
most code is shared. User auth isn't hooked up yet, nor has it been
tested.

main.go

@@ -87,7 +87,7 @@ type appContext struct {
 	webFS          httpFS
 	cssClass       string // Default theme, "light"|"dark".
 	jellyfinLogin  bool
-	users          []User
+	adminUsers     []User
 	invalidTokens  []string
 	// Keeping jf name because I can't think of a better one
 	jf               *mediabrowser.MediaBrowser
@@ -450,7 +450,7 @@ func start(asDaemon, firstCall bool) {
 			user.UserID = shortuuid.New()
 			user.Username = app.config.Section("ui").Key("username").String()
 			user.Password = app.config.Section("ui").Key("password").String()
-			app.users = append(app.users, user)
+			app.adminUsers = append(app.adminUsers, user)
 		} else {
 			app.debug.Println("Using Jellyfin for authentication")
 			app.authJf, _ = mediabrowser.NewServer(serverType, server, "jfa-go", app.version, "auth", "auth", timeoutHandler, cacheTimeout)
@@ -645,6 +645,9 @@ func flagPassed(name string) (found bool) {
 // @securityDefinitions.basic getTokenAuth
 // @name getTokenAuth
 
+// @securityDefinitions.basic getUserTokenAuth
+// @name getUserTokenAuth
+
 // @tag.name Auth
 // @tag.description -Get a token here if running swagger UI locally.-