Allow parsing + before Float32/Float64 values

Why it matters

This feature solves the problem where float values with a leading plus sign (e.g. +1.23) were not correctly parsed. By supporting the + sign, it improves data compatibility and usability when importing or processing float numbers that include explicit positive signs.

How to use it

No special configuration is required. ClickHouse now natively supports parsing Float32 and Float64 values with an optional leading + sign in queries and data inputs.