Add com.snowflake.snowpark.functions.countDistinct

[sfc-gh-lbravozuniga]

Please answer these questions before submitting your pull requests. Thanks!

1. What GitHub issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Fixes # SCT-2681

2. Fill out the following pre-review checklist:

   • [X] I am adding a new automated test(s) to verify correctness of my new code
   • [ ] I am adding new logging messages
   • [ ] I am adding a new telemetry message
   • [ ] I am adding new credentials
   • [ ] I am adding a new dependency

3. Please describe how your code solves the related issue.

   Added com.snowflake.snowpark.functions.countDistinct, it is an alias of count_distinct function.

Pre-review checklist

(For Snowflake employees)

• [X] This change has passed precommit
• [ ] I have reviewed code coverage report for my PR in (Sonarqube)