**Description:**
Adds support for `-` in `cast_to_number`. Before it only worked if `arg` is `Infinity`. Now it uses a recursive call on `arg` so it works for expressions like `-5`, `-[]` etc.
This change is important because negative number literals (e.g. `-5`) are a `UnaryExpr` with `op`=`-` & `arg`=`5`, unless you apply `expr_simplifier` pass or something else that uses it.
