This PR adds a CosmosDb-specific projection facility based on Microsoft's ChangeFeedProcessor library.

ChangeFeedProcessor:

• Equinox.Cosmos.Projection library (only targets netstandard2.0)
• Adds an eqx project cosmos subcommand to Equinox.Tool, with appropriate logging
• Provide a dotnet new eqxprojector template in https://github.com/jet/dotnet-templates which provides a basic template
• Lag reporting is not working Troubleshooting GetEstimatedRemainingWorkPerPartitionAsync Azure/azure-documentdb-changefeedprocessor-dotnet#126

Kafka Projector:

• Provide a basic Kafka publisher impl in e.g. in an Equinox.Projection.Kafka
• Checkpointing needs to be surfaced in a way such that we checkpoint on high watermark of what's confirmed accepted into kafka (the kafka acks may be out of order)
• Likely also add aneqx project cosmos kafka option that will provide a baseline projector facility
• Provide a -k switch https://github.com/jet/dotnet-templates that builds on the basic eqxprojector, providing a basis for customization based on the eqx project cosmos kafka feature

The Kafka support targets Confluent.Kafka 1.1.0-beta3