Support loading metadata columns from stage into table for Snowflake

[pankajkoti]

Adds support to load metadata columns like METADATA$FILENAME,
METADATA$FILE_ROW_NUMBER, etc. from stage into target table
while natively loading files into Snowflake tables. Read more at:
https://docs.snowflake.com/en/user-guide/querying-metadata#example-3-loading-metadata-columns-into-a-table

Note that, you cannot specify both validation_mode and
metadata_columns together in the Snowflake load options
because when we need to load metadata_columns, we need
to explicitly name the metadata columns in the COPY INTO
sql statement and such a transformed SQL statement does not
allow specifying VALIDATION_MODE with it. It's a limitation
for Snowflake queries.
The transformed SQL appears like in the snippet in the following link:
https://docs.snowflake.com/en/user-guide/querying-metadata#example-3-loading-metadata-columns-into-a-table

closes: #1982

[pankajkoti]

The transformed COPY INTO command executed is like the below when metadata_columns are specified:

'COPY INTO <TABLE_NAME> FROM (SELECT $1,$2,METADATA$FILENAME,METADATA$FILE_ROW_NUMBER,METADATA$FILE_CONTENT_KEY,METADATA$FILE_LAST_MODIFIED,METADATA$START_SCAN_TIME FROM @SANDBOX.<schema_name>.<stage_name>/sample.csv) '

[pankajkoti]

Sample load output with metadata columns

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.73% 🎉

Comparison is base (4176abf) 89.54% compared to head (09d2b10) 90.28%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2023      +/-   ##
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+ Coverage   89.54%   90.28%   +0.73%     
==========================================
  Files          75       75              
  Lines        4296     4324      +28     
  Branches      531      537       +6     
==========================================
+ Hits         3847     3904      +57     
+ Misses        354      332      -22     
+ Partials       95       88       -7     

Flag	Coverage Δ
PythonSDK	90.28% <100.00%> (+0.73%)	⬆️

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Files Changed	Coverage Δ
python-sdk/src/astro/databases/snowflake.py	85.33% <100.00%> (+1.13%)	⬆️
python-sdk/src/astro/options.py	97.61% <100.00%> (+0.05%)	⬆️

... and 6 files with indirect coverage changes

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[Andrew-Wichmann]

Nice! Thank you!