SNOW-4174500: Fix nested udxf inheriting inaccessable stage path

[sfc-gh-mayliu]

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

   Fixes SNOW-4174500

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
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   • If this is a new feature/behavior, I'm adding the Local Testing parity changes.
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3. Please describe how your code solves the related issue.

   Please write a short description of how your code change solves the related issue.

Bug

When a stored procedure declares IMPORTS, Snowflake resolves those to absolute app-package stage paths and seeds them into session._import_paths. Any nested UDxF registered inside that procedure with no explicit imports= argument inherits those paths verbatim into its DDL, i.e:

CREATE TEMPORARY FUNCTION snowpark_temp_udtf_xyz
  IMPORTS = ('@APP_PKG."APP_ARTIFACTS_V1.0".APP_FILES/pandas_helper.py')

The executing role can't access that pandas_helper.py path on stage, so Snowflake rejects the DDL. This affects apply_in_pandas, session.udf.register, session.udtf.register, and any other UDxF registration that omits imports=.

Fix

Inside a stored procedure, the platform already extracts every staged import to a local temp directory (sys._xoptions["snowflake_import_directory"]).
https://docs.snowflake.com/en/developer-guide/udf/python/udf-python-examples#reading-a-statically-specified-file-using-imports

The fix looks for each stage path's file there and re-uploads it to the session's own temp stage, so that the executing role always owns the redirected path and replaces the inaccessible original path. No behavioral change outside a stored procedure since this fix targets nested UDxF calls. Can be disabled via session.conf.set("restage_stored_procedure_imports", False)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 95.83333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.47%. Comparing base (adaaef2) to head (5b005f8).

Files with missing lines	Patch %	Lines
src/snowflake/snowpark/session.py	95.83%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4412   +/-   ##
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  Coverage   95.46%   95.47%           
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  Files         176      176           
  Lines       45271    45295   +24     
  Branches     7759     7766    +7     
=======================================
+ Hits        43220    43245   +25     
+ Misses       1270     1269    -1     
  Partials      781      781           

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