### _Why are the changes needed?_
As title.
With this pr, customer can execute SCALA code with `confOverlay`.
```
kyuubi.operation.language=SCALA
```
execute PYTHON code with
```
kyuubi.operation.language=PYTHON
```
### _How was this patch tested?_
- [x] Add some test cases that check the changes thoroughly including negative and positive cases if possible
- [ ] Add screenshots for manual tests if appropriate
- [ ] [Run test](https://kyuubi.readthedocs.io/en/master/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#4639 from turboFei/init_scala.
Closes#4639
cdf828f9a [fwang12] add ut
f4f2bc883 [fwang12] doc
2fe8a1659 [fwang12] save
f840cb4d9 [fwang12] conf overlay
eb49537ea [fwang12] conf overlay
Authored-by: fwang12 <fwang12@ebay.com>
Signed-off-by: fwang12 <fwang12@ebay.com>
0fdf145e29