Implement Char Function Similar to One in Mysql #7486 (sundyli)

Why it matters

This feature provides ClickHouse users with a convenient way to convert integer ASCII codes into their corresponding characters, enabling easier string manipulations and compatibility with MySQL string functions.

How to use it

Use the char function by passing integer arguments representing ASCII codes. The function returns a string containing the characters for those codes. For example:

SELECT char(65, 66, 67); -- returns 'ABC'