Tensorflow metadata

[RustedBones]

• clean protoc configuration
• download tensorflow metadata from released artifact
• package tensorflow medatada with scio-tensorflow
• depend on scio-tensorflow as provided in scio-parquet
• use tfmd (tensorflow metadata) schema instead of me.lyh:parquet-tensorflow
• create tensorflow example-parquet support based on official avro-parquet implementation

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (d394cca) 63.43% compared to head (efa1a5f) 63.42%.
Report is 2 commits behind head on main.

❗ Current head efa1a5f differs from pull request most recent head 4337c24. Consider uploading reports for the commit 4337c24 to get more accurate results

Files	Patch %	Lines
...ify/scio/parquet/tensorflow/ParquetExampleIO.scala	84.61%	2 Missing ⚠️
...spotify/scio/parquet/read/ReadSupportFactory.scala	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4944      +/-   ##
==========================================
- Coverage   63.43%   63.42%   -0.01%     
==========================================
  Files         288      288              
  Lines       10807    10805       -2     
  Branches      785      778       -7     
==========================================
- Hits         6855     6853       -2     
  Misses       3952     3952              

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[clairemcginty]

With such a big refactoring, it could be good to have a test validating that files written using .saveAsParquetExampleFile in Scio <= 0.13.1 can still be read using sc.parquetExampleFile going forward

[RustedBones]

Added and it works!
It is actually a good thing that the original schema was not stored in the extraMetadata as reusing the key would have created parsing issue (users would have to provide the schema as projection).

[RustedBones]

There is something in the official documentation:

• If a Feature K doesn't exist in an example, a K-specific default will be used, if configured.
• If a Feature K exists in an example but contains no items, the intent is considered to be an empty tensor and no default will be used.

Right now, parquet storage doesn't do distinction between feature without items and omitted feature. Reconstructed Example omits the feature, which may not be what we want

[RustedBones]

This seems to be useless as the job is not used in the sdf implementation