Add find_first lambda function

[feilong-liu]

Fix #18304.

Add an UDF find for array, which returns the first array element which matches the predicate. Returns null if no match found.

• find_first(array(T), function(T, boolean)) -> T
  Returns the first element which returns true for function(T, boolean). Return null if no match found.

• find_first(array(T), startIndex, function(T, boolean)) -> T
  If startIndex>0, find match starting at the startIndex in array until the end of array. If startIndex<0, find match starting
  at the absolute(startIndex) counting from last, until the start of array. Array is 1 indexed, startIndex=0 will return exception.

Test plan - (Please fill in how you tested your changes)

Add unit tests.

== RELEASE NOTES ==

General Changes
* Add an UDF find for array
 Finds the first array element which matches a predicated. Returns null if no match found.
 
.. function:: find_first(array(E), function(T,boolean)) -> E

    Returns the first element of ``array`` which returns true for ``function(T,boolean)``. Returns ``NULL`` if no such element exists.

.. function:: find_first(array(E), index, function(T,boolean)) -> E

    Returns the first element of ``array`` which returns true for ``function(T,boolean)``. Returns ``NULL`` if no such element exists.
    If ``index`` > 0, the search for element starts at position ``index`` until the end of array.
    If ``index`` < 0, the search for element starts at position ``abs(index)`` counting from last, until the start of array.

        SELECT find_first(ARRAY[3, 4, 5, 6], 2, x -> x > 0); -- 4
        SELECT find_first(ARRAY[3, 4, 5, 6], -2, x -> x > 0); -- 5
        SELECT find_first(ARRAY[3, 4, 5, 6], 2, x -> x < 4); -- NULL
        SELECT find_first(ARRAY[3, 4, 5, 6], -2, x -> x > 5); -- NULL

[kaikalur]

Also please see if we need these specializations or if we can just use boxed types and write a single method (for example like we do in: ArrayReduceFunction)

[kaikalur]

Hmm - you should not need two functions for this, I don't think. Just make it a variadic function and check in the constructor?

[feilong-liu]

Get an error when trying to combine the two classes to be one, there is the same error in PR #15170 too from the conversation.

[pranjalssh]

Some nits

[feilong-liu]

Also please see if we need these specializations or if we can just use boxed types and write a single method (for example like we do in: ArrayReduceFunction)

Updated the diff. I see that there are some conversations in PR #15170 about boxed type vs. implementing multiple functions regarding performance which ends up in implementing multiple implementations. Should we still keep the same tradeoff here?

[kaikalur]

Also don't forget to add documentation in the rst file

[feilong-liu]

Also please see if we need these specializations or if we can just use boxed types and write a single method (for example like we do in: ArrayReduceFunction)

Updated the diff. I see that there are some conversations in PR #15170 about boxed type vs. implementing multiple functions regarding performance which ends up in implementing multiple implementations. Should we still keep the same tradeoff here?

Discussed with @kaikalur offline, we are to keep it consistent with PR #15170 and implement multiple functions.

[feilong-liu]

Also don't forget to add documentation in the rst file

Add document to rst file.

[pranjalssh]

Dont have strong opinions of 2 vs 1 file. You could write multiple @ScalarFunction annotations but not very clean

[kaikalur]

Looks good!