[SPARK-30617][SQL] Stop check values of spark.sql.catalogImplementation to improve expansibility

[WeiWenda]

What changes were proposed in this pull request?

When user config spark.sql.catalogImplementation with value not in in-memory/hive, check if below properties is configured. If configured then instantiate SessionState with provided Class, or else throw Exception as usual.

spark.sql.catalogImplementation.[value of spark.sql.catalogImplementation].builder
spark.sql.catalogImplementation.[value of spark.sql.catalogImplementation].externalCatalog

For example:

spark.sql.catalogImplementation = qihoo
spark.sql.catalogImplementation.qihoo.builder = org.apache.spark.sql.qihoo.QihooSessionStateBuilder
spark.sql.catalogImplementation.qihoo.externalCatalog = org.apache.spark.sql.qihoo.QihooExternalCatalog

Why are the changes needed?

We have implemented a complex ExternalCatalog which is used for retrieving multi isomerism database's metadata(sush as elasticsearch、postgresql), so that we can make a mixture query between hive and our online data. But as spark require that value of spark.sql.catalogImplementation must be one of in-memory/hive, we have to modify SparkSession and rebuild spark to make our project work.
Finally, we hope spark removing above restriction, so that it's will be much easier to let us keep pace with new spark version. Thanks!

Does this PR introduce any user-facing change?

no

How was this patch tested?

no

[AmplabJenkins]

Can one of the admins verify this patch?

[dongjoon-hyun]

Hi, @WeiWenda . I'll close this PR. Please open to the master branch first.
For all patches, we need to consider master first. Otherwise, we will miss something in 3.0.0.

[WeiWenda]

Thanks for your remind. I have opened a new pr at #27349