[SPARK-15547][SQL] nested case class in encoder can have different number of...

[SPARK-15547][SQL] nested case class in encoder can have different number of fields from the real schema

## What changes were proposed in this pull request?

There are 2 kinds of `GetStructField`:

1. resolved from `UnresolvedExtractValue`, and it will have a `name` property.
2. created when we build deserializer expression for nested tuple, no `name` property.

When we want to validate the ordinals of nested tuple, we should only catch `GetStructField` without the name property.

## How was this patch tested?

new test in `EncoderResolutionSuite`

Author: Wenchen Fan <wenchen@databricks.com>

Closes #13474 from cloud-fan/ordinal-check.