improve events subscriptions

[4meta5]

Might be nice to have a higher level api for subscribing to a particular event type and doing the decoding, but no need for this PR

_Originally posted by @ascjones in #126 (comment)

We need an iterator-like API for subscribing to events for @sunshine-protocol CC @dvc94ch

[dvc94ch]

@ascjones any progress on dynamic event decoding using scale-info?

[ascjones]

No. It depends on integrating scale-info with substrate which I haven't even started yet. I'm busy with ink! 3.0 work atm but will see if I can block out some time to look into it.

[dvc94ch]

Any progress? We need more sophisticated event subscriptions, and without this, they won't work very reliably.

[ascjones]

@dvc94ch I've started experimenting with this: I'm part way through implementing SCALE encoding for scale-info here: paritytech/scale-info#19.

I'll do some more on it next week and let you know how I progress.

[jsdw]

We have this now, and in the not distant future we'll start relyong on scale_value and so may provide back Value's for unknown events rather than skipping over the bytes, for more flexibility (but also for more robust/deduplicated decode logic)