[SPARK-4293][SQL] Make Cast be able to handle complex types.

Inserting data of type including `ArrayType.containsNull == false` or `MapType.valueContainsNull == false` or `StructType.fields.exists(_.nullable == false)` into Hive table will fail because `Cast` inserted by `HiveMetastoreCatalog.PreInsertionCasts` rule of `Analyzer` can't handle these types correctly.

Complex type cast rule proposal:

- Cast for non-complex types should be able to cast the same as before.
- Cast for `ArrayType` can evaluate if
  - Element type can cast
  - Nullability rule doesn't break
- Cast for `MapType` can evaluate if
  - Key type can cast
  - Nullability for casted key type is `false`
  - Value type can cast
  - Nullability rule for value type doesn't break
- Cast for `StructType` can evaluate if
  - The field size is the same
  - Each field can cast
  - Nullability rule for each field doesn't break
- The nested structure should be the same.

Nullability rule:

- If the casted type is `nullable == true`, the target nullability should be `true`
I don't think we need to handle the case specially the same as other expressions.
The element data of the type `ArrayType.containsNull == false` are never `null`, so always `elementCast(v)` will be called.