Appids with invalid UTF-8 bytes are not matched by regex

[TimDeve]

Similarly to #114 I was having problems with some shortcuts and despite the changes in #114 I found that the regex used to extract data out of shortcuts.vdf does not match when the appid contains invalid UTF-8 bytes. I have posted an example here with appids from my shortcuts.vdf.

As I have some time on my hand I wrote a binary parser for vdf files. Would you be interested in a PR?