Convert field bracketed arrays to type generics for JSDocs compatibility

[alanbixby]

JSDocs does not handle Type[] syntax correctly when used as a field (an object attribute or an optional function parameter).

The problematic behavior is apparent in our return types that include cursors:

data is an Array- of what?

Switching to Array<Type> syntax, JSDocs cooperates and shows that it is an array of GroupJoinRequests with a corresponding hyperlink:

I have also fixed a number of types that were capitalized (Number -> number), and array parameters with no types defined.

Returns using bracketed syntax do not need to be changed.

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This pull request only affects JSDocs documentation, index.d.ts did not require modification.