feat(Apollo): make use of generic type on MutationOptions in Apollo#mutate

[Merott]

Without this the MutationOptions generic takes the default type of { [key: string]: any; } which isn't very useful. This is needed by the updateQueries option to detect the right type for the mutationResult data object.

[apollo-cla]

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[kamilkisiela]

Hi! I will update everything around Angular and TypeScript soon, then I'm going to merge this :)

[kamilkisiela]

@Merott Hi! :) Could you rebase it?

[Merott]

I just rebased, but in doing so I also removed the explicit types on the method, since TypeScript can infer them perfectly fine, and making them explicit makes human errors more likely.

The same could be done for query, mutate and subscribe. I've verified that on my machine but not committed. I'd be happy to commit and push if you want.