[Robust Fabric Config] Refactor chaincode configuration

[aklenik]

Context

This issue is part of the Fabric network configuration schema refactoring task.

Currently, chaincodes of a channel are configured with array notation. Moreover, there is a constraint, that the contractID must be unique on a network level, since it's referenced in the user callback, identifying the channel and CC at the same time.

First, the contractID is optional, it defaults to the id of the CC. This can be confusing, and it's easy to forget. Second, the array notation makes it harder to look up CCs.

Possible fix

Since the channels.mychannel.chaincodes property is not part of the CCP of the SDK, we can refactor it the following way:

channels:
  mychannel:
    chaincodes:
      simpleContract:  # This is the now mandatory contractID
        id: ... # The rest is the same

Benefits

The unique contract ID is now explicit and mandatory. And it's unique on the channel level due to object key uniqueness. Checking the network-level uniqueness is easier now.
Plus, it's easier to check whether a given contractID exists, no need to iterate through everything.

Environment

• Version: 0.1.0

[nklincoln]

Replaced with #940