Support Arithmetic function SIGN

[jbl428]

Motivation

• Support an arithmetic function SIGN.

Modifications

• Add jpql model and serializer for SIGN

Commit Convention Rule

• Please commit your modification based by conventional commit:

Commit type	Description
feat	New Feature
fix	Fix bug
docs	Documentation only changed
ci	Change CI configuration
refactor	Not a bug fix or add feature, just refactoring code
test	Add Test case or fix wrong test case
style	Only change the code style(ex. white-space, formatting)
chore	It refers to minor tasks such as library version upgrade, typo correction, etc.

• If you want to add some more commit type please describe it on the Pull Request

Result

• The arithmetic function sign is added.

Closes

• Support Arithmetic function SIGN #595