feat(furc/IR): move IR from furlang to furc

First try baby, whoo!

furc/src/main.cpp

@@ -1,3 +1,4 @@
+#include "furc/back/ir.hpp"
 #include "furc/front/lexer.hpp"
 #include "furc/front/parser.hpp"
 #include "furlang/arena.hpp"
@@ -6,17 +7,15 @@ int main(void) {
     furlang::arena arena;
 
     std::string_view content = R"(
-        func main(argc: u64) -> s32 pre(arc > 1) {
+        func main(argc: u64) -> s32 {
             x: s32 = 1 + 2 * 3;
-            println(x);
             return if (x == 9) 1 else 0;
         }
     )";
 
-    furc::lexer  lexer  = { "<AK>", content };
-    furc::parser parser = { std::move(lexer), arena };
-
-    auto program = parser.parse();
+    furc::lexer     lexer    = { "<AK>", content };
+    furc::parser    parser   = { std::move(lexer), arena };
+    furc::ir_module irModule = furc::ir_generator::generate(parser.parse());
 
     return 0;
 }