Implement ICS 3 connection spec in ics-poc branch

[majecty]

Datagram

I'll implement datagrams using transaction in Foundry.

• ConnOpenInit Implement connOpenInit datagram in the ICS connection spec #157
• ConnOpenTry Implement connOpenTry datagram in the ICS connection spec #166
• ConnOpenAck Implement ConnOpenAck datagrain in the ICS Connection spec #180
• ConnOpenConfirm Implement ConnOpenConfirm datagram #185

Queries

I'll implement queries using Foundry's RPC.

• queryConnection Impement queryConnection and queryClientConnections #195
• queryClientConnections Impement queryConnection and queryClientConnections #195

Questions

• I don't understand why they are verifying other chain's consensus state. I'll omit it in the POC implementation.
• In the connection spec, they are saying, "Each chain has knowledge of and has agreed to its identifier on the other chain."
  We might need some authorization logic to make only allowed users be able to create connections.

Not todo

• Connection spec is specifying version. Since it is not needed in POC implementation, I'll skip it.

Reference

https://github.com/cosmos/ics/tree/master/spec/ics-003-connection-semantics

[junha1]

Who will implement followings?

• verifyClientConsensusState()
• verifyConnectionState()
• verifyChannelState()
• verifyPacketData()
• verifyPacketAcknowledgement()
• verifyPacketAcknowledgementAbsence()
• verifyNextSequenceRecv()

[majecty]

DONE. I added PR links in the description.