[SPARK-10035] [SQL] Parquet filters does not process EqualNullSafe filter.

As I talked with Lian,

1. I added EquelNullSafe to ParquetFilters
 - It uses the same equality comparison filter with EqualTo since the Parquet filter performs actually null-safe equality comparison.

2. Updated the test code (ParquetFilterSuite)
 - Convert catalyst.Expression to sources.Filter
 - Removed Cast since only Literal is picked up as a proper Filter in DataSourceStrategy
 - Added EquelNullSafe comparison

3. Removed deprecated createFilter for catalyst.Expression

Author: hyukjinkwon <gurwls223@gmail.com>
Author: 권혁진 <gurwls223@gmail.com>

Closes #8275 from HyukjinKwon/master.