* Remove signature helper completely from Invidious
The official way to reproduce video with Invidious now is by using
Invidious Companion which uses Youtube.JS with a Javascript Interpreter
that can successfully decrypt youtube video URLs.
Sig helper has not been used for a long time, is beyond broken and no
one has plans to fix it and maintain it.
* Remove DECRYPT_FUNCTION and shrink player function
* remove `sp = cfr[sp]`
* Improve message
07f3894a71