ams: allow bootloader to merely approximate correct target firmware

fusee: fix loader stub

loader: refactor to remove fake namespaces

loader: refactor ro manager/improve accuracy

spl: refactor for accuracy/move into libstrat

docs: add hactool to list of build dependencies (#1662) ...

Co-authored-by: ndeadly <24677491+ndeadly@users.noreply.github.com>

os: add FlushDataCache

strat: use m_ for member variables

svc: use m_ for member variables

sdmmc: use m_ for member variables

kern: fix some lingering non-m_ member variables

exo/vapours: refactor member variables to m_ over this->

libstrat: remove lingering debugging edits

ams: replace most remaining operator & with std::addressof

settings: fix correctness issue in LazyFileAccessor

strat: refactor address taking of form &var[...]

strat: always use explicit result namespacing

settings: implement KeyValueStore (#1659) ...

* settings: implement KeyValueStore and dependencies

* settings: update KeyValueStore for recent refactoring

* settings: address feedback

sm: remove apm:p compatibility hack ...

Homebrew which would hang when doing this were compiled with libnx < 3.0.0.

Homebrew which is compiled with < 3.0.0 cannot send messages to sm, because
of the incorrect serialization problem (which required homebrew recompile when
12.0.0 released).

Thus, there is no case where this makes a difference.

kern: put rela in bss ...

NOTE: This saves ~0x4000 of space at the cost of crimes against the linker script.

kern: clean up mesosphere buildscript

kern: tidy up capability calc

fusee: fix loader stub size alignment

git subrepo push libraries ...

subrepo:
  subdir:   "libraries"
  merged:   "0a4c2759a"
upstream:
  origin:   "https://github.com/Atmosphere-NX/Atmosphere-libs"
  branch:   "master"
  commit:   "0a4c2759a"
git-subrepo:
  version:  "0.4.1"
  origin:   "???"
  commit:   "???"

os: fix mutex push/pop prototypes

git subrepo push libraries ...

subrepo:
  subdir:   "libraries"
  merged:   "80d72af9f"
upstream:
  origin:   "https://github.com/Atmosphere-NX/Atmosphere-libs"
  branch:   "master"
  commit:   "80d72af9f"
git-subrepo:
  version:  "0.4.1"
  origin:   "???"
  commit:   "???"

ams.mitm: avoid using std::unordered_map, it manifests exception code

cs: prevent exceptions from manifesting

boot: save 12KB

erpt: save 8KB