Split Parquet code into multiple files

[bmcdonald3]

The Parquet code currently exists as a single monolithic file, which makes it difficult to manage and is not good practice.

By splitting the Parquet code into multiple files, each limited to a distinct functionality, we can make the code easier to maintain/keep track of/modify. Initially, I am splitting the code into three files (1) read (2) write (3) utility.

There will be follow up PRs to further improve the readability/maintainability of this code.