adding appName alias for Session.builder.app_name

[sfc-gh-mrojas]

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 #1348

2. Fill out the following pre-review checklist:

   • [ ] 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.

This just adds an alias such that appName will be the same as app_name

[sfc-gh-mrojas]

@sfc-gh-aalam is this ready to merge? or there is something else missing