Some work on Scripts

notable changes:
- rename `bt-connect` to `bt_connect`
- rename `music` to `media` and make it generic instead of checking
  Spotify
- make separate script to set background to a preset black image
- make all shebangs "#!/usr/bin/env sh"

Scripts/.local/scripts/speed

@@ -1,2 +1,2 @@
-#!/bin/bash
+#!/usr/bin/env sh
 wget -nv --show-progress -O /dev/null "https://aryadevchavali.com/resources/Table-of-Integrals.pdf"