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ARROW-13646: [Go][Parquet] adding the parquet metadata package

Here's the next chunk of code following the merging of #10716

Thankfully the metadata package is actually relatively small compared to everything else so far.

@emkornfield @sbinet @nickpoorman for visibility

Closes #10951 from zeroshade/parquet-metadata-package

Authored-by: Matthew Topol <mtopol@factset.com>
Signed-off-by: Matthew Topol <mtopol@factset.com>