These two classes are very similar, so let's merge them.

Macros should be all upper-cased. This is also kind of a wart that's
been sticking out for quite a while now (we avoid prefixing
underscores).

This adds a WiiWad constructor that takes a BlobReader, so that the
class can be used with more than just files from the host filesystem.

Required for using WiiWad with WADs from update partitions.

Some code was calling more than one of these functions in a row
(in particular, FileUtil.cpp itself did it a lot...), which is
a waste since it's possible to call stat a single time and then
read all three values from the stat struct. This commit adds a
File::FileInfo class that calls stat once on construction and
then lets Exists/IsDirectory/GetSize be executed very quickly.

The performance improvement mostly matters for functions that
can be handling a lot of files, such as File::ScanDirectoryTree.

I've also done some cleanup in code that uses these functions.
For instance, some code had checks like !Exists() || !IsDirectory(),
which is functionally equivalent to !IsDirectory(), and some
code was using File::GetSize even though there was an IOFile
object that the code could call GetSize on.

These prefixes were inconsistent with the rest of Dolphin.

I'm also renaming VolumeWiiCrypted to VolumeWii because of 1113b13.

These were not caught by the lint script while it was broken.

We can simply put ReadSwapped directly in IBlobReader.

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.