Add Function Repeat Related to Issue-6648 #6999 (flynn)

Why it matters

The repeat function addresses the need for easily creating repeated string patterns within SQL queries. This is useful for data formatting, generating test strings, or constructing repeated character sequences without manual concatenation or external processing.

How to use it

Use the repeat function by specifying the string to be repeated as the first argument and the number of repetitions as the second argument. Example usage:

SELECT repeat('abc', 3);
-- Result: 'abcabcabc'