ft: introduce modrm macro for leaner matching

All instructions which use a modrm instruction
for memory reads from or into a register can
make use of this macro

src/disasm_macros.rs

@@ -0,0 +1,8 @@
+#[macro_export]
+/// Generate an Opcode for 'normal' ModRM instructions with mem access and a reg
+macro_rules! modrm {
+    ($self:ident, $variant:ident) => {{
+        let (idx, reg) = $self.parse_modrm_byte();
+        Opcode::$variant(idx, Register::by_id(reg))
+    }};
+}