Added arrayDistinct function

Why it matters

The arrayDistinct function removes duplicate elements from an array, enabling users to easily obtain arrays with unique values. This simplifies data processing and analysis by eliminating duplicates within array data structures.

How to use it

Use the arrayDistinct function by passing an array as its argument in your SQL queries. For example:

SELECT arrayDistinct([1, 2, 2, 3, 3, 3, 4])

This will return the array with duplicate elements removed.