SNOW-1842839: Add support for Series.str.pad

[sfc-gh-helmeleegy]

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

   Fixes SNOW-1842839

2. Fill out the following pre-review checklist:

   • I am adding a new automated test(s) to verify correctness of my new code
     • If this test skips Local Testing mode, I'm requesting review from @snowflakedb/local-testing
   • I am adding new logging messages
   • I am adding a new telemetry message
   • I am adding new credentials
   • I am adding a new dependency
   • If this is a new feature/behavior, I'm adding the Local Testing parity changes.
   • I acknowledge that I have ensured my changes to be thread-safe. Follow the link for more information: Thread-safe Developer Guidelines

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

   Add support for Series.str.pad.

[sfc-gh-nkrishna]

One nit, but LGTM! Nice to see how it all ties together :)

[sfc-gh-nkrishna]

Nit: Can we have this ValueError mention the API?

Suggested change

	raise ValueError("Invalid side")
	raise ValueError("Invalid side for Series.str.pad")

[sfc-gh-helmeleegy]

This is mimicking the exact error message raised by native pandas! so I didn't want to change it.

[sfc-gh-lmukhopadhyay]

LGTM!