Allow create_project to rerun safely #453

Is your feature request related to a problem? Please describe.
Having the create_project method on the Feast Client fail when a project exists is important, but its also a pain in development. It means one part of the code in a notebook should be skipped every time.

Describe the solution you'd like
It would be convenient to be able to run create_project multiple times without having the second call throw an exception.

Something like

client.create_project("my-project", skip_if_exists=True)

Describe alternatives you've considered
Alternatively we can use set_project and only create the project lazily when its needed.