* am/am: Avoid redundant copy in GetProgramInfoFromCia()
We can just use a reference to the title metadata. Avoids copying
several data entries and std::vector instances that don't need to be
copied.
* hle/service: Avoid redundant copying of std::string
GetUserPath() returns the path as a reference, so we can make use of
said reference to avoid making copies.
* Core: pass down Core::System reference to all services
This has to be done at once due to unified interface used by HLE/LLE switcher
* apt: eliminate Core::System::GetInstance
* gpu_gsp: eliminate Core::System::GetInstance in service
* hid: eliminate Core::System::GetInstance
* nwm: eliminate Core::System::GetInstance
* err_f: eliminate Core::System::GetInstance
These functions are pretty much identical to BeginImportProgram and EndImportProgram.
We don't need to do anything special in EndImportProgramWithoutCommit and CommitImportPrograms because we don't need to implement the two-phase title installation that the 3DS uses to prevent corruption of the title.db.
FS subfiles are created with File::OpenSubFile, they have a start offset that must be added to all read/write operations.
The implementation in this commit is done using a new FileBackend that wraps the FS::File along with the start offset.
Instead of using an unsigned int as a parameter and expecting a user to
always pass in the correct values, we can just convert the enum into an
enum class and use that type as the parameter type instead, which makes
the interface more type safe.
We also get rid of the bookkeeping "NUM_" element in the enum by just
using an unordered map. This function is generally low-frequency in
terms of calls (and I'd hope so, considering otherwise would mean we're
slamming the disk with IO all the time) so I'd consider this acceptable
in this case.
There were a few places where nested namespace specifiers weren't being
used where they could be within the service code. This amends that to
make the namespacing a tiny bit more compact.
