Investigate addition of IBCModule v2 application interface

[damiannolan]

Summary

IBC eureka/v2 protocol will introduce a new Packet type and commitment structure design informed by cosmos/ibc#1149
As the current IBCModule interface defined in 05-port/types depends on the current(classic) IBC packet, the proposed changes lends itself to introducing a new IBCModule interface with a more fine-grained and reduced API.

Proposal

This proposal has been informed by proof-of-concept work which experimented with a v2 IBCModule interface including variations of the following methods.
This should be further explored within the context of IBC protocol v2 / eureka and vetted for viability. The IBCModule interface is reduced to 4 concise methods for packet handling, eliminating handshake handlers from the IBC app design.

type IBCModule interface {
	OnSendPacket(
		ctx context.Context,
		sourceID string,
                 destinationID string,
		sequence uint64,
		data channeltypesv2.PacketData,
		signer sdk.AccAddress,
	) error

	OnRecvPacket(
		ctx context.Context,
		sourceID string,
                 destinationID string,
		data channeltypesv2.PacketData,
		relayer sdk.AccAddress,
	) channeltypes.RecvPacketResult

	OnAcknowledgementPacket(
		ctx context.Context,
		sourceID string,
                 destinationID string,
		data channeltypesv2.PacketData,
		acknowldgement []byte,
		relayer sdk.AccAddress,
	) error

	OnTimeoutPacket(
		ctx context.Context,
		sourceID string,
                 destinationID string,
		data channeltypesv2.PacketData,
		relayer sdk.AccAddress,
	) error
}

The above is a recommended starting point and intended to be tuned as progress is made on the surrounding parts of the implementation, and information is gathered.

A mock stubbed IBC app module can be created to implement the methods and run tests before moving forward with touching existing IBC apps.

• Add OnSendPacket to IBCModule v2 interface #7408
• Add OnRecvPacket to IBCModule v2 interface #7409
• Add OnAcknowledgementPacket to IBCModule v2 interface #7410
• Add OnTimeoutPacket to IBCModule v2 interface #7411

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For Admin Use

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[damiannolan]

Needs discussion: decision is to explore if its viable to use an adapter pattern to wrap v1 module and route code through

[chatton]

We came to the conclusion that it is not possible to use the adapter pattern as there is no direct equivalent to the MsgSendPacket operation in the IBCModule(V1) api, the keeper SendPacket function could be called at any time.

All interface functions have been implemented, closing this issue.