Remove superfluous Event/Extrinsic decoding APIs?

[jsdw]

Events and extrinsics both now provide:

// return the values of the fields in the event as a Composite
fn field_values(&self) -> Result<scale_value::Composite<scale_value::scale::TypeId>, Error>
// return the values of the fields in the event as some type E
fn as_event<E: StaticEvent>(&self) -> Result<Option<E>, Error>fn as_pallet_event<E: DecodeWithMetadata>(&self) -> Result<E, Error>
// try to decode the event into some specific pallet::Event
fn as_pallet_event<E: DecodeWithMetadata>(&self) -> Result<E, Error>
// try to decode the event into the root runtime::Event
fn as_root_event<E: RootEvent>(&self) -> Result<E, Error>

Ie, we have 4 different ways to decode events (and the same interface exists foer calls for consistency).

• as_root_n is the most generally useful way to statically decode things nowadays I think, and renders as_pallet_n redundant. And moreso, as_pallet_n fns may decode things into the wrong types if the types happen to align closely enough, so I think it's a bit of a footgun. (ie if you try to decode some extrinsic into pallet_a::Call, it will succeed even if it was actually from pallet_b::Call as long as the types line up for the variant we're decoding)
• as_n (ie as_event and as_extrinsic) are used in all of the find() functions, which are quite nice ergonomically, so I'd keep them for now just for that reason.
• field_values (for events and extrinsics) is the only way to dynamically decode fields, which Probably makes marginally more sense than decoding the entire outer variant (you can check the variant/pallet names separately already anyway).

So, I'd propose that we remove as_pallet_extrinsic and as_pallet_event for now. I'd like to remove more, but the find() APIs are just a little too appealing to want to remove, though one can manually iterate extrinsics/events, and search/decode based on pallet and variant name)