feat(tazjin/rlox): Add support for statements

First part of
https://craftinginterpreters.com/statements-and-state.html

Supports print statements, as well as evaluation for the sake of
it (i.e. future side-effects).

Change-Id: Ic6653b568f98d6cfe3f297615b7113c0ba1d9a70
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2287
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

users/tazjin/rlox/src/errors.rs

@@ -4,6 +4,7 @@ pub enum ErrorKind {
     UnterminatedString,
     UnmatchedParens,
     ExpectedExpression(String),
+    ExpectedSemicolon,
     TypeError(String),
 }