Ajm (#1456)

* ajm: Initial ajm implementation

* AJM code improvements (#1453)

* Fix sideband buffer order (#1454)

* ajm: Attempt to add gapless support

* ajm_at9: Return superframes decoded in a single job

* WIP (#1460)

* Fix gapless decode and combine split buffers

* Fixed linux build

* fix number of samples reported with gapless decoding

* fixed number of remaining samples calculation

should fix the small crackling sounds that play every now and again

* refactor half ajm

* refactored most of ajm

* refactored ajm

* clang-format, in-repo libatrac9, removed debug stuff

---------

Co-authored-by: auser1337 <aaravsandhu10@outlook.com>
Co-authored-by: Vladislav Mikhalin <mikhalinvlad@gmail.com>
Co-authored-by: IndecisiveTurtle <geoster3d@gmail.com>

.gitmodules

@@ -98,4 +98,7 @@
 [submodule "externals/discord-rpc"]
 	path = externals/discord-rpc
 	url = https://github.com/shadps4-emu/ext-discord-rpc.git
-	shallow = true
+	shallow = true
+[submodule "externals/LibAtrac9"]
+	path = externals/LibAtrac9
+	url = https://github.com/shadps4-emu/ext-LibAtrac9.git