refactor(tazjin/rlox): Move entrypoints into interpreters

Right now this introduces a simple mechanism to flip between the
interpreters.

Change-Id: I92ee920c53d76ab6b664ac671993a6d6426af61a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2412
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

users/tazjin/rlox/src/bytecode/mod.rs

@@ -0,0 +1,7 @@
+//! Bytecode interpreter for Lox.
+//!
+//! https://craftinginterpreters.com/chunks-of-bytecode.html
+
+pub fn main() {
+    unimplemented!()
+}