Orderer v3: remove kafka support

[tock-ibm]

In v3 we will remove support for kafka as an orderer consensus protocol.

• [x] Disable kafka as a consensus protocol
• [x] Remove all integration tests that use kafka
• [x] Move integration tests that do consensus type migration to raft, use solo-raft migration
• [x] Remove kafka from integration tests infrastructure
• [x] Remove kafka code from orderer / consensus
• [x] Clean up the code for kafka to raft migration, but keep some features of it that may be useful for migration from protocol to protocol (e.g. raft -> bft)
• [x] Remove kafka from local config objects and methods
• [x] Remove kafka from (shared) channel config objects and methods
• [x] Remove (or depricate) kafka from protos
• [x] Remove kafka from configtxgen
• [x] Remove kafka dependencies from build infrastructure - docker-thirdparty
• [x] Update documentation
• [x] Remove kafka from fabric-config project PR 59
• [ ] Revise/review SDKs to work with new protos that do not include kafka

In Epic: #3511

[MayRosenbaum]

One more thing we have to do is to remove KafkaBrokers struct from fabric-protos.