ThirdPartyServices: SetContactMethods for setting, enable/disable

replace AddContactMethods with a more generalised SetContactMethods,
which can set (or leave alone) contact method addresses/names/ids and
set (or leave alone) contact preferences. A little awkward to use, but
works everywhere, and now a bunch of Jellyseerr integration features are
present for Ombi (which they should've been anyway).

discord.go

@@ -32,6 +32,17 @@ type DiscordDaemon struct {
 	retryOpts                     *common.MustAuthenticateOptions
 }
 
+func EmptyDiscordUser() *DiscordUser {
+	return &DiscordUser{
+		ID:            "",
+		Username:      "",
+		Discriminator: "",
+		Lang:          "",
+		Contact:       false,
+		JellyfinID:    "",
+	}
+}
+
 func newDiscordDaemon(app *appContext) (*DiscordDaemon, error) {
 	token := app.config.Section("discord").Key("token").String()
 	if token == "" {