Add create_database_if_not_exist

[prabirshrestha]

Add create_database_if_not_exist method so one can call one function instead of having custom if else code.

[brianheineman]

@prabirshrestha thank you for the feature request. Every function requires duplication for the async and blocking APIs as well as associated testing and documentation. For the time being, I'm inclined to leave the API as is.