runtime, macros: unify NaN-boxed value API under ValueVariant trait

fix-bytecode/src/disassembler.rs

@@ -2,7 +2,7 @@ use std::fmt::Write;
 
 use colored::Colorize as _;
 
-use crate::{InstructionPtr, Op, OperandType, Continuation};
+use crate::{Continuation, InstructionPtr, Op, OperandType};
 
 pub trait DisassemblerContext {
     fn resolve_string(&self, id: u32) -> &str;