The old implementation of this was not able to distinguish between
a title that had the common key index set to 1 because it actually
was Korean and a title that had the common key index set to 1 due to
fakesigning. This new implementation solves the problem by
decrypting a content with each possible common key and checking
which result matches the provided SHA-1 hash.
The problem that the old implementation causes has only been reported
to affect a certain pirated WAD of Chronos Twins DX (WC6EUP), but it's
possible that the problem would start affecting more WADs if we add
support for the vWii common key (which uses index 2). Adding support
for the vWii common key would also prevent us from using the simpler
solution of always forcing the index to 0 if the title is not Korean.
Removes redundant initializers from the constructor and provides
initializers for all members that don't already have one for consistency
(and deterministic initial state).
Given the volume verifier has quite a few non-trivial object within it,
it's best to default the destructor within the cpp file to prevent
inlining complex destruction logic elsewhere, while also making it nicer
if a forward-declared type is ever used in a member variable.
