Add ParquetMetadataDoFn

[kellen]

Reads parquet metadata, when possible, from the file footer.

[codecov]

Codecov Report

❌ Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 61.59%. Comparing base (b566764) to head (c40b13d).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...potify/scio/parquet/syntax/SCollectionSyntax.scala	96.87%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5820      +/-   ##
==========================================
+ Coverage   61.49%   61.59%   +0.09%     
==========================================
  Files         314      315       +1     
  Lines       11437    11469      +32     
  Branches      830      828       -2     
==========================================
+ Hits         7033     7064      +31     
- Misses       4404     4405       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[kellen]

TODO is to add some better syntax for this from String -> metadata and/or glob -> resourceid -> metadata

[clairemcginty]

strong opinion loosely held:

IMO, this function is niche enough that instead of adding an extra SCollection[String] helper, we should just add a function to [FileSCollectionFuctions] like readFiles that just transforms SCollection[String] -> SCollection[ReadableFile]. Then the user can just do

sc
  .parallelize(paths)
  .readFiles
  .parquetMetadata

(approving anyway because I don't feel super strongly about this.)

[kellen]

I guess there is already a ReadableFIle => A version of readFiles in which case

sc
  .parallelize(paths)
  .readFilesParquetMetadata() // or readParquetMeatadata, or even better than either of these parquetMetadata

Where readFilesParquetMetadata still needs to be in the parquet project, with an implicit/syntax, and we need to separately provide a ReadableFile => ParquetMetadata function