These prefixes were inconsistent with the rest of Dolphin.

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

This commit moves the write function to where it should be (IOS),
especially when ES::ImportTicket() is the only place to use it.

Prevents misusing the ticket import function, and removes one unsafe
direct write to the NAND that does not go through IOS.

This also fixes the destination path: the session root is the one which
should be used for determining the ticket path, not the configured one.

The whole NANDContentLoader stuff is truly awful and will be removed
as soon as possible.

For now, this fixes a bug that was exposed by std::optional::operator*.

* Less code and logic duplication.

* Fixes a bug with the data dir not being created, steps being done in
  the wrong order.

Just like DeleteTitle, Using CNANDContentManager is overkill,
inefficient and useless. And it results in a few failures in
situations where a delete should just always work.

But here it gets bonus points, because it manages to actually use
the TMD for deleting contents, when IOS does none of that and just
deletes files ending with .app in the title content directory. :)

These are all specific to ES and belong there.

The SharedContentMap and UIDSys classes were also modernised.

This keeps the ES specific NAND code in a single place and makes it
reusable. Eventually, other ES specific code will be moved to it.

This should allow channels to be copied to the SD properly.