Analogy interface is too inflexible

[danieldk]

While reimplementing finalfusion-inspector in Rust, I bumped into a small annoyance. The analogy method takes an array of &str:

query: [&str; 3]

However, oftentimes you have a [String; 3]. We should relax this type to:

query: [impl AsRef<str>; 3]

This should not break the API, since it allows a superset of types of the original signature.