feat(tazjin/rlox): Implement function call evaluation

Change-Id: I6767c3a1a9654475b4066415f8c026b9c5b5907a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2382
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

users/tazjin/rlox/src/errors.rs

@@ -12,6 +12,7 @@ pub enum ErrorKind {
     UndefinedVariable(String),
     InternalError(String),
     InvalidAssignmentTarget(String),
+    RuntimeError(String),
 }
 
 #[derive(Debug)]