feat(parquet): Add support for Page Indexes

[zeroshade]

Rationale for this change

Adds support for writing and retrieving Page Indexes from parquet files

What changes are included in this PR?

Added new writer properties to enable writing PageIndexes either as default or for specific columns.
Added RowGroupPageIndexReader, ColumnIndexReader, OffsetIndexReader to access page index information.

Are these changes tested?

Yes, extensive unit tests have been added including round trip tests and encryption/decryption tests.

Are there any user-facing changes?

no. Just new functions available.

closes #33

[kou]

(Sorry, I couldn't review this carefully... I took a look at all changes but I don't have enough knowledge of the Parquet specification and Go. And this change is too large for me... I hope that others can review this.)

[zeroshade]

Thanks for taking a look at all @kou!

@wgtmac and @pitrou I specifically tagged you both for review here given your Parquet experience hoping that one or both of you would be able to take a look at this from that perspective. Much of this is based on the way that Parquet C++ handles Page Indexes

[zeroshade]

I'd like to get this in before I kick off the next release in the next week or so. Would anyone be free to do a review soon?

[zeroshade]

Thanks for the review @lidavidm!!