remove a bunch of 'any' types

[dynst]

Description:

Replace a bunch of any types with either unknown or a more specific type.

But two are harder to replace, changing them causes type errors:

https://github.com/ReactiveX/rxjs/blob/c15b37f81ba5f5abea8c872b0189a70b150df4cb/packages/observable/src/observable.ts#L262 https://github.com/ReactiveX/rxjs/blob/c15b37f81ba5f5abea8c872b0189a70b150df4cb/packages/observable/src/observable.ts#L498

  Type 'Subscriber<T>' is not assignable to type 'Subscriber<unknown>'.
    Type 'unknown' is not assignable to type 'T'.

BREAKING CHANGE:

Related issue (if exists):

Part of the 8.x roadmap in #6367

Replace all external uses of any with unknown. (This could likely be non-breaking, FWIW.)