Make session in searchSchema configurable

[aurlien]

This change solves https://github.com/neo4j-graphql/neo4j-graphql-js/issues/570, by adding sessionParams as a parameter to the searchSchema function.

When working on a multi-database project, searchSchema could be used like this to target a non-default database foo:

searchSchema({ driver, schema, sessionParams: { database: 'foo' } })

[aurlien]

@johnymontana Is there anything more I should do to get this and https://github.com/neo4j-graphql/neo4j-graphql-js/pull/578 approved?

[michaeldgraham]

https://github.com/neo4j-graphql/neo4j-graphql-js/issues/608