chore(tvix/eval): wire things up for development flow

This creates a REPL which outputs compiled bytecode, constants, and VM
results for code snippets.

Change-Id: If63f79a961456afd6a4cdf59b994107ff7ab8b47
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6072
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

tvix/eval/src/main.rs

@@ -48,7 +48,7 @@ fn run_prompt() {
 
 fn run(code: String) {
     match eval::interpret(code) {
-        Ok(result) => println!("=> {:?}", result),
+        Ok(result) => println!("=> {}", result),
         Err(err) => eprintln!("{}", err),
     }
 }