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_arithmetic.cpp

@@ -1,5 +1,3 @@
-// https://github.com/google/googletest/blob/master/googletest/docs/advanced.md#value-parameterized-tests
-
 #include <chrono>
 #include <iostream>
 #include <random>
@@ -119,7 +117,7 @@ class ArithmeticTests : public testing::TestWithParam<IntegerParam> {
   // Called before the first test in this test suite.
   static void SetUpTestSuite() {
     runtime_thread = std::make_unique<std::thread>(std::thread(GoalTest::runtime_no_kernel_jak1));
-    compiler = std::make_unique<Compiler>(GameVersion::Jak1);
+    compiler = std::make_unique<Compiler>(GameVersion::Jak1, emitter::InstructionSet::X86);
     runner = std::make_unique<GoalTest::CompilerTestRunner>();
     runner->c = compiler.get();
   }