[Umbrella] Session / System Control Statement Support

[yaooqinn]

Code of Conduct

• I agree to follow this project's Code of Conduct

Search before asking

• I have searched in the issues and found no similar issues.

Describe the proposal

Introduce session and system statements to support changing engine or session behavior

MORE DETAIL OR DESIGN DOC WILL BE UPDATED HERE LATER

Task list

TODO

Are you willing to submit PR?

• Yes I am willing to submit a PR!

[pan3793]

#3926 is the first step to achieve this feature