### What changes were proposed in this pull request?
Currently, pure SQL users are short of ways to see the Hadoop configurations which may affect their jobs a lot, they are only able to get the Hadoop configs that exist in `SQLConf` while other defaults in `SharedState.hadoopConf` display wrongly and confusingly with `<undefined>`.
The pre-loaded ones from `core-site.xml, hive-site.xml` etc., will only stay in `sparkSession.sharedState.hadoopConf` or `sc._hadoopConfiguation` not `SQLConf`. Some of them that related the Hive Metastore connection(never change it spark runtime), e.g. `hive.metastore.uris`, are clearly global static and unchangeable but displayable I guess. Some of the ones that might be related to, for example, the output codec/compression, preset in Hadoop/hive config files like core-site.xml shall be still changeable from case to case, table to table, file to file, etc. It' meaningfully to show the defaults for users to change based on that.
In this PR, I propose to support get a Hadoop configuration by SET syntax, for example
```
SET mapreduce.map.output.compress.codec;
```
### Why are the changes needed?
better user experience for pure SQL users
### Does this PR introduce _any_ user-facing change?
yes, where retrieving a conf only existing in sessionState.hadoopConf, before is `undefined` and now you see it
### How was this patch tested?
new test
Closes#32144 from yaooqinn/SPARK-35044.
Authored-by: Kent Yao <yao@apache.org>
Signed-off-by: Kent Yao <yao@apache.org>
f32114d17e