[C++] [Python] Set up testing for backwards compatibility of the parquet reader

[asfimport]

Given the recent parquet compat problems, we should have better testing for this.

For easy testing of backwards compatibility, we could add some files (with different types) written with older versions, and ensure they are read correctly with the current version.

Similarly as what Kartothek is doing: https://github.com/JDASoftwareGroup/kartothek/tree/master/reference-data/arrow-compat

An easy way would be to do that in pyarrow and add them to /pyarrow/tests/data/parquet (we already have some files from 0.7 there).

Reporter: Joris Van den Bossche / @jorisvandenbossche

_{Note: This issue was originally created as ARROW-5915. Please see the migration documentation for further details.}