pegasus: add new module and small updates

[cmitu]

Since the static binaries provided upstream are no longer working on newer RaspiOS or on 32bit ARM, create a standard scriptmodule to build Pegasus with pegasus-fe-dev. The new scriptmodule is meant to work similarly to the es/es-dev pair, only one can work at a time and they share a set of common functions. Note that due to the Qt5 version needed, the new scriptmodule is meant to be used on Debian 11/Ubuntu 22.04 and later.

Modified the original scriptmodule and added a theme download function, using @mmatyas's themes. More can be found at [2].

A 2nd commit adds pegasus-fe as an auto-start item, similar to Kodi/ES, while fixing the spelling of 'EmulationStation'.

Notes:

• the pegasus-fe launcher doesn't need the previous TTY set-up, it's now handled by runcommand.
• sometimes the /dev/dri/card0 is not the right card node since the order of the cardX inodes is not guaranteed. Find the right card node dynamically (see [1]) and tell Qt about it with a minimal config file used in the launcher

[1] https://forums.raspberrypi.com/viewtopic.php?t=351263 [2] https://github.com/mmatyas/pegasus-theme-gallery-db/blob/master/repos.txt

Closes #3586.

[cmitu]

@joolswills I added the rename for ES in a separate commit.