Implement the channel message handlers

[ancazamfir]

Summary

Implement ics04-channel module message handlers.
Prerequisite: #105

Proposal

• Implement the dispatch, process, keeper etc for all messages

  • channOpenInit Implement ChanOpenInit handler #97
  • channOpenTryClientState: replace frozen_height() and is_frozen() with confirm_not_frozen() #545
  • channOpenAck Add missing Channel Open/Close handlers informalsystems/hermes#618
  • channOpenConfirmMake token transfer events compatible with latest ibc-go #618
  • channCloseInitMake token transfer events compatible with latest ibc-go #618
  • channCloseConfirmMake token transfer events compatible with latest ibc-go #618

• Introduce the channel context in mocks

• Add minimal tests until MBT is available

• Maintain consistency with the connection module artifacts

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