Add compatibility test for $stdDevSamp (second pass)

[eerxuan]

Part of #19.

Category: core / operator / expressions / accumulator

Add compatibility test coverage for the $stdDevSamp expression operator.

[Jhr-4]

Hello, I am interested in working on this issue of adding compatibility tests for $stdDevSamp.

I have reviewed the test coverage guidelines and plan to implement extensive test cases for this function. I will follow the guidelines mentioned to ensure comprehensive testing for multiple cases such as datatype coverage, type mismatches, null/missing fields, and more. I will also include the special case of an array of size 1, resulting in division by 0.

Could this issue please be assigned to me? Thank you!

[Jhr-4]

PR See: #661