Fixed a critical issue

[dead8309]

1. Fixed an issue with media rpc where large image:

Shows correct image for sometime then it starts showing app logo.

Blinks every 5 second on discord app.
It was consuming more webhook resources by sending the image every 5 second.

Replaced previous practice with SharedPreferences to store artwork data as

"${appPackageName}:${mediaTitle}"

2. Fixed Custom Webhook setting

Now you can easily paste a discord webhook link and app will use it to send data for Media and Apps Rpc