Alpha release for Temporal Server.

Release Highlights

1. Temporal Web is now supported to work this release
2. Renamed Domain to Namespace
3. Simplified getting started experience to have docker pre baked with 'default' namespace
4. Use standard grpc health service endpoint
5. Other internal renaming

Helpful links to get you started with Temporal

Temporal Docs
Server
Java SDK
Java Samples
Go SDK
Go Samples
Helm Chart

Docker images for this alpha release (use tag 0.21.0):

Server
Server With Auto Setup
CLI (tctl)
Admin-Tools

Things we are still working on

1. We are still working and cleaning some internal API contracts. So more breaking changes are coming. So please don't use this for production setup yet.
2. Stress and Performance testing.