[SPARK-10195] [SQL] Data sources Filter should not expose internal types

[JoshRosen]

Spark SQL's data sources API exposes Catalyst's internal types through its Filter interfaces. This is a problem because types like UTF8String are not stable developer APIs and should not be exposed to third-parties.

This issue caused incompatibilities when upgrading our spark-redshift library to work against Spark 1.5.0. To avoid these issues in the future we should only expose public types through these Filter objects. This patch accomplishes this by using CatalystTypeConverters to add the appropriate conversions.

[SparkQA]

Test build #41482 has finished for PR 8403 at commit 6af0a45.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #41486 has finished for PR 8403 at commit 1a3d053.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #41490 has finished for PR 8403 at commit c3fb4eb.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[cloud-fan]

Like the buildScan in data source, we shoud not expose internal types outside spark sql, but we also need to provide the ability to build efficient data source by using internal types directly(no conversions) for our build-in data source or advanced users.

There maybe some cases that user need the internal types in Filter to avoid converions and speed up operations, I think we need to improve our data source API to make this stuff more flexible.
cc @liancheng

[rxin]

This is once for query - isn't it? It'd make sense to specialize the input, but I don't think it's worth it for the filter pushdowns.

[liancheng]

This PR LGTM.

@cloud-fan Same opinion as @rxin. Filter push-down itself isn't a critical path.

[rxin]

I've merged this.