Split up Parquet reader tests

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**

While working on this PR with @sdf-jkl
- https://github.com/apache/arrow-rs/pull/9118

I noticed that the existing end to end arrow_reader tests in arrow_reader/mod.rs are non ideal:
1. 5000 lines of tests in a that single file (start at 1500 -> 6500)
2. Have specific data tests, fuzz tests, and everything in between

This makes them both hard to navigate as well as evaluate our current test coverage

A taste:
https://github.com/apache/arrow-rs/blob/a4b04c912d3f904dcf92894e81f11f576929fcb5/parquet/src/arrow/arrow_reader/mod.rs#L4046-L4045

**Describe the solution you'd like**
I would like the reader tests split into multiple modules, so that it is easier to find the relevant content and tests

**Describe alternatives you've considered**

**Additional context**