dbms

Proposed changes

Close related #7513 (replace it with issue number if it exists).

Describe the overview of changes, and introduce why we need it.

Types of changes

What types of changes does your code introduce to Doris?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality

Use case:
Add the ability to search for an element in an array and retrieve back the array index.
As per the PostgreSQL documentation:

array_position ( anycompatiblearray, anycompatible [, integer ] ) → integer

Returns the subscript of the first occurrence of the second argument in the array, or NULL if it's not present

It would be great to implement test case reduction strategies in SQLancer itself. The advantage of doing this in SQLancer, rather than an external tool like C-Reduce, is that we have all the information on whether a specific bug is still triggered (e.g., that two queries should yield the same result) and that the reduction can likely go further than when having an external interestingness test (e.