ams: update build system to add generic-fallback support

sf: Change interface definition methodology (#1074) ...

* sf: Begin experimenting with new interface declaration format

* sf: convert fs interfaces to new format

* sf: finish conversion of libstrat to new definitions

* sf: convert loader to new format

* sf: convert spl to new format

* sf: update ncm for new format

* sf: convert pm to new format

* sf: convert ro/sm to new format

* sf: update fatal for new format

* sf: support building dmnt under new scheme

* sf: update ams.mitm for new format

* sf: correct invocation def for pointer holder

* fs: correct 10.x+ user bindings for Get*SpaceSize

fs: implement AccessLog, enable for File operations

Switch atmosphere's build target to C++20. (#952) ...

* ams: update to build with gcc10/c++20

* remove mno-outline-atomics

* ams: take care of most TODO C++20s

* fusee/sept: update for gcc10

* whoosh, your code now uses pre-compiled headers

* make: dependency fixes

ams: centralize system thread definitions

hos: change initialization API ...

This was needed to make stratosphere buildable with debugging on.

os:: assertions rely on GetCurrentThread() working, and this requires
the global os resource manager to be constructed. However, __appInit executes
before global constructors. We now require that hos::InitializeForStratosphere()
be called before anything else is done. This initializes the os resource manager,
sets the hos version for libnx, and may do more things in the future.

TODO: Consider replacing __appInit/__appExit with ams:: namespace functions in general,
and wrap them so that we guarantee hos::InitializeForStratosphere is called first, and
generally ensure a consistent stratosphere environment.

pgl: Reimplement the pgl sysmodule (#896) ...

* pgl: add skeleton folder to stratosphere

* pgl: Add service interface for IShellInterface

* pgl: begin skeletoning shell service, implement two commands.

* pgl: Implement three more commands.

* pgl: implement bool tracking commands

* pgl: Implement TriggerApplicationSnapShotDumper

* pgl: implement InitializeProcessControlTask

* pgl: Implement pgl::srv::Initialize

* pgl: Implement main()

* pgl: Implement (Get)ShellEventObserver

* pgl: implement LaunchProgramFromHost, GetHostContentMetaInfo

* pgl: Implement ProcessControlTask

* settings: fix duplicate object name

* pgl: fix minor bugs in impl