add cardinality
function to calculate total distinct elements in an array
#937
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Which issue does this PR close?
Completes a task in #463
Rationale for this change
This PR introduces a new function, cardinality, which returns the number of distinct elements in a array
What changes are included in this PR?
Added the cardinality function.
Updated the Python bindings in functions.py and provided unit tests for cardinality in test_functions.py.
Updated the documentation (expressions.rst) to include examples on how to use the new cardinality function.
Are there any user-facing changes?
The cardinality function is now available for users working with arrays. It is exposed both in Rust and Python, allowing users to obtain the number of distinct elements in their DataFusion queries.
There are no breaking changes to public APIs.