Add `Platform: Flash` to annotations automatically for Ruffle about libtas

[Randomno]

Related to #551 but doesn't look like that's going anywhere, so this is a better option

[vadosnaprimer]

Hmm, actually including the executable name would be neater since we could deduce the platform directly that way.

[vadosnaprimer]

I found out it's already there and we should be using it

libTAS/src/program/movie/MovieFileHeader.cpp

Line 133 in c890635

config.setValue("game_name", context->gamename.c_str());