Support federated search

[ellnix]

In our current state, the multi-search path is acting as a sort of federated search, except without proper ranking rules.

We should deprecate the old #each and #to_a on MultiSearchResult and add a separate path for federated search.

[wesharper]

Would this rely on this PR or is the library sufficiently divergent?

[ellnix]

Would this rely on this PR or is the library sufficiently divergent?

@wesharper It does, I pinged the author of the PR. Of course there's nothing preventing me from implementing it on this gem before the PR is done, but I think it would violate the spirit of FOSS collaboration.

[wesharper]

Of course there's nothing preventing me from implementing it on this gem before the PR is done, but I think it would violate the spirit of FOSS collaboration.

@ellnix totally agree here. Happy to support any way I can, we've been antsy to start using this!