Support domain socket

[daixiang0]

Describe the proposal

Ref dapr/dapr#2864

UPDATE:
DAPR_HTTP_ENDPOINT and DAPR_GRPC_ENDPOINT should also work with a local socket path instead of HTTP.

Users can specify the value of the socket path with the following value unix:/tmp/my-dapr.sock

Release Note

RELEASE NOTE: ADD support domain socket.

[mukundansundar]

This needs a change in dapr/cli before this can be picked up.

[mthmulders]

I believe domain socket support was added to Java in version 16 with JEP-380. As a consequence, if we want to support older versions of Java as well, we should have a fallback strategy to HTTP or gRPC.