goalc: Get CodeTester tests passing on Arm64 (only targetting macOS atm) (#3290)

This PR does the following:
- Designs a mechanism by which arm64 instructions can be encoded and
emitted
- Dispatch our higher-level instruction emitting calls to either x86 or
arm64 instructions depending on what the compiler is set to (defaults to
x86)
- Bare minimum scaffolding to get the arm64 instructions successfully
executing atleast on apple silicon
- Implement enough instructions to get the codetester test suite passing
on arm

test/goalc/test_compiler.cpp

@@ -2,6 +2,6 @@
 #include "gtest/gtest.h"
 
 TEST(CompilerAndRuntime, ConstructCompiler) {
-  Compiler compiler1(GameVersion::Jak1);
-  Compiler compiler2(GameVersion::Jak2);
+  Compiler compiler1(GameVersion::Jak1, emitter::InstructionSet::X86);
+  Compiler compiler2(GameVersion::Jak2, emitter::InstructionSet::X86);
 }