This is a first step at fixing the conceptual insanity that is our
handling of service and IPC calls. For now, interfaces still directly
derived from Session because we don't have the infrastructure to do it
properly. (That is, Processes and scheduling them.)

All service calls in the CTR OS return result codes indicating the
success or failure of the call. Previous to this commit, Citra's HLE
emulation of services and the kernel universally either ignored errors
or returned dummy -1 error codes.

This commit makes an initial effort to provide an infrastructure for
error reporting and propagation which can be use going forward to make
HLE calls accurately return errors as the original system. A few parts
of the code have been updated to use the new system where applicable.

One part of this effort is the definition of the `ResultCode` type,
which provides facilities for constructing and parsing error codes in
the structured format used by the CTR.

The `ResultVal` type builds on `ResultCode` by providing a container for
values returned by function that can report errors. It enforces that
correct error checking will be done on function returns by preventing
the use of the return value if the function returned an error code.

Currently this change is mostly internal since errors are still
suppressed on the ARM<->HLE border, as a temporary compatibility hack.
As functionality is implemented and tested this hack can be eventually
removed.

These functions are not referred to by their linkage name outside of the translation unit, so they can be marked as static.

seems simple enough

Pica/citra-qt: Replace command list view and command list debugging code with something more sophisticated.

This cleans up the mess that address reading/writing had become and makes the code a *lot* more sensible.
This adds a physical<->virtual address converter to mem_map.h. For further accuracy, we will want to properly extend this to support a wider range of address regions. For now, this makes simply homebrew applications work in a good manner though.

GSP: Fix a major regression introduced in ffda035c, due to which no display transfers were triggered at all anymore.

While it was some nice and fancy template usage, it ultimately had many practical issues regarding length of involved expressions under regular usage as well as common code completion tools not being able to handle the structures.
Instead, we now use a more conventional approach which is a lot more clean to use.

GSP: Cleaned up code and added additional comments.

GSP: Removed unnecessary TODO comment.

GSP: Changed u32 iterators in TriggerCmdReqQueue to unsigned.

- Various other cleanups.

Core: Added a comment to explain the logic for the RunLoop iterations.

Anonymous structs are not standard C++, hence don't use them.

- Previously, used a hard-coded shared memory handle of 0x10002000 (as used by libctru homebrew)

GSP: Added name for shared memory.

GSP: Cleaned up assertion message.