accept stage paths starting with / for GET

[sfc-gh-tvanderkooy]

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

   Fixes SNOW-1793953 (SNOW-1889627: SNOW-1793953: Allow relative path starting with / for GET #2888)

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.

   This builds on the changes from Add support for snow:// stage paths #1346 to allow / as a remote path prefix so file.get('/some/path')will not try to prepend @ to the path. This form of relative path is valid in some native application uses cases.

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[sfc-gh-tvanderkooy]

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