Function resolve_usize_value

Resolve a `serde_json::Value` that is either a literal number or a string containing a `${{ }}` expression to a `usize`. Examples: - `Value::Number(20)` → `Ok(20)` - `Value::String("${{ params.pr_size }}")` → resolves expression → `Ok(n)`

(
    value: &serde_json::Value,
    params: &HashMap<String, Value>,
    state: &HashMap<String, Value>,
    matrix_values: Option<&HashMap<String, Value>>,
    task_context: Option<&TaskExpressionCo