Function awint_internals::bits_upper_bound

pub fn bits_upper_bound(len: usize, radix: u8) -> Result<usize, SerdeError>

This is used for quickly calculating the maximum number of bits needed for a string representation of a number in some radix to be represented. This may give more bits than needed, but is guaranteed to never underestimate the number of bits needed. Returns None if we see memory exhaustion