[SPARK-2917] [SQL] Avoid table creation in logical plan analyzing for CTAS

Oh, I understood. But I'd like to make that as 2 independent PRs:
* Revert the `SchemaRDDLike.scala` and `SQLQuerySuite.scala`, and only keep the logic of table creation move from `HiveMetastoreCatalog.scala` to the physical operator `CreateTableAsSelect.scala`
* Update the #1847 for supporting the `EXPLAIN` for `command` (e.g. `ctas`, `InsertIntoTable`, `WriteToFile` etc.)

What do you think about this?