Add accessor for footer after a file is closed

[asfimport]

I'm storing metrics along with Parquet files in Iceberg and need to get the metrics from the Parquet footer just after writing a file. Parquet should be able to return the footer after closing a file so the caller doesn't have to open the file just after writing.

Reporter: Ryan Blue / @rdblue
Assignee: Ryan Blue / @rdblue

Related issues:

• Release Parquet Java 1.10 (blocks)

PRs and other links:

• PR #457

_{Note: This issue was originally created as PARQUET-1215. Please see the migration documentation for further details.}

[asfimport]

Ryan Blue / @rdblue:
Merged #457. Thanks to @zivanfi and @gszadovszky for the reviews!