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

lsp/state/workspace.cpp

@@ -298,8 +298,9 @@ void Workspace::start_tracking_file(const LSPSpec::DocumentUri& file_uri,
       const std::string progress_title =
           fmt::format("Compiling {}", version_to_game_name_external(game_version.value()));
       m_requester.send_progress_create_request(progress_title, "compiling project", -1);
-      m_compiler_instances.emplace(game_version.value(),
-                                   std::make_unique<Compiler>(game_version.value()));
+      m_compiler_instances.emplace(
+          game_version.value(),
+          std::make_unique<Compiler>(game_version.value(), emitter::InstructionSet::X86));
       try {
         // TODO - this should happen on a separate thread so the LSP is not blocking during this
         // lengthy step