Added SnowflakeDbDataReader implementation of GetEnumerator using DbEnumerator class

[sfc-gh-jmartinezramirez]

Description

Added implementation of GetEnumerator using DbEnumerator class.

Checklist

• [x] Code compiles correctly
• [x] Code is formatted according to Coding Conventions
• [x] Created tests which fail without the change (if possible)
• [x] All tests passing (dotnet test)
• [x] Extended the README / documentation, if necessary
• [x] Provide JIRA issue id (if possible) or GitHub issue id in PR name

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.89%. Comparing base (3d0194c) to head (408dc90). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1031 +/- ## ========================================== + Coverage 85.86% 85.89% +0.02% ========================================== Files 118 118 Lines 11456 11455 -1 Branches 1146 1146 ========================================== + Hits 9837 9839 +2 + Misses 1335 1333 -2 + Partials 284 283 -1 ```

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