fix(caching): Take operation into account for cache prefix (#1365)

[dulnan]

Fixes #1365.

[klausi]

Thanks, at first I did not understand that you can actually send different operation names with multiple queries.

Not sure why you would do that, as the graphql server will only execute one?

Anyway, I have a test case now that I will push in a follow-up PR and we can do this!