ICS28: Remove CCV channel state

[mpoke]

There is not need to keep extra state for the CCV channel, i.e., ChannelStatus.

On the provider chain, the CCV channel is set to

• INITIALIZING in onChanOpenTry; we can use TRYOPEN from ICS4
• VALIDATING in onChanOpenConfirm; we can use OPEN from ICS4; plus, the channel is added to the chainToChannel map
• INVALID is never used

On the consumer chain, the CCV channel is set to

• INITIALIZING in onChanOpenInit; we can use INIT from ICS4
• VALIDATING when receiving the first VSCPacket (see onRecvVSCPacket); at the same time though, providerChannel is also set, so we can use that instead
• INVALID is never used

[mpoke]

Furthermore, if a packet sent by the consumer CCV module after onChanOpenAck cannot arrive at the provider CCV module before onChanOpenConfirm, then the consumer CCV module should set providerChannel in onChanOpenAck. The only reason providerChannel is set when receiving the first VSCPacket is to make sure the CCV channel endpoint on the provider is also OPEN.

@AdityaSripal

• Do we want to disable User TXs on the consumer chain until the CCV channel endpoint on the provider is OPEN? Or is it sufficient to wait for the CCV channel endpoint on the consumer to be OPEN?
• Can a packet sent after OpenChanAck be relayed before OpenChanConfirm?