Bug#1029953: game-data-packager: add support for itch.io as a game store

[James Addison]

Source: game-data-packager
Severity: wishlist

As mentioned during discussion[1] in #1026277, it'd be nice to add support
for itch.io[2] as an additional online game store in game-data-packager.

(I'll take a look into implementing this soon, although I can't guarantee
that that'll result in a patch / merge request)

[1] - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1026277#15

[2] - https://itch.io/