Direct access to the WAD bytes is required to read contents with proper
padding data (since they can sometimes end up being outside of the
data app section). Allowing the whole buffer to be accessed directly
would be error prone, so this commit adds GetContent() to WiiWAD
for getting raw content data by index.
We already have a TMDReader, so let's actually use it.
And move ESFormats to IOS::ES, since it's definitely part of IOS.
This adds a DiscIO dependency on Core which will be fixed in a
follow-up PR.
These functions don't actually depend on any state from the class
instance, so they don't really belong in the header, and are just
an implementation detail.
