[GIE] Start Cypher-only service

[longbinlai]

Now we have provided GIE service in Python SDK that supports starting Gremlin-only service using:

graphscope.gremlin(g)

or

graphscope.interactive(g, with_cypher=False)  # False is the default option and can be omitted

and Gremlin/Cypher services using

graphscope.interactive(g, with_cypher=True)

We can add an api that starts Cypher-only service., like:

graphscope.cypher(g)