feat(fromEvent): add FromEvent type export

[huan]

This PR tries to implement the discussion from #9

[andywer]

Great stuff! Haven't tested it yet, but looks good.

I only reverted the version bump as a best practice (imagine having three open PRs and each bumping the version while you aren't even sure they will be released together)

[andywer]

Really tiny suggestion: rxjsFromEvent is quite a handful. What would you think about renaming the import alias to rxFromEvent?

It's just two letters difference, but I think it would make the code feel "friendlier".

[huan]

Absolutely agree with this.

Have renamed rxjsFromEvent to rxFromEvent from both the README and the source code.

[huan]

Great to know that you think this PR is good!

I have followed your suggestion and finished the modifications.

Please let me know if there's any other suggestion so we can continue improving it, and I'm looking forward to installing this feature from NPM! (before the RxJS v8 remove the fromEvent<T> for Node.js EventEmitter ;-)

[andywer]

@huan Cool. I'm just thinking what the next steps are.

How about this: Let's already publish a pre-release version to npm (v1.5.0-rc?) from the feature branch, without updating the latest tag on npm, so you can install it manually from npm, but it's only opt-in until we merge and publish the update.

Btw, I didn't quite get this bit:

(before the RxJS v8 remove the fromEvent for Node.js EventEmitter ;-)

[huan]

Thanks, publishing a pre-release version to npm as v1.5.0-rc is good to me, I'll test it in my project after it has been published.

Btw, I didn't quite get this bit:
"before the RxJS v8 remove the fromEvent for Node.js EventEmitter ;-)"

The fromEvent<T>() that can only work with my Node.js EventEmitter code has been flagged as deprecated, and said that it will be removed after RxJS v8:

/** @deprecated Do not specify explicit type parameters. Signatures with type parameters that cannot be inferred will be removed in v8. */

See: https://github.com/ReactiveX/rxjs/blob/ecbc6c1178b528b95c44aed5c145b4e6cf7df173/src/internal/observable/fromEvent.ts#L82

I don't know if the RxJS team has already a better solution for this, but for now, it's the only one I can use.

[andywer]

@huan Sorry for the delay! Published commit e581f3a as [email protected] under tag testing.

[huan]

I have used it and everything working as expected so far:

https://github.com/wechaty/puppet/blob/f0b28519b072586f48febb383322c5e06cc9deda/tests/from-event-type.spec.ts#L33

Thank you very much for publishing this new feature!