Add DAG flow

[Spycsh]

Type of Change

feature

Description

Microservices dataflow is organized in a DAG, we expose two ways: Python API or Yaml config to define that. Further features are to be done including Ingress/Egress, megaservice API etc.
usage e.g.

Yaml

    - (s1, s5) >> s2
    - s2 >> (s3, s4)
    - s3 >> s4

equivalent to

Python

service_builder = ServiceBuilder(port=1234, hostfile=None)
s1 = BaseService(id="s1", endpoint="http://localhost:8081/v1/add")
s2 = BaseService(id="s2", endpoint="http://localhost:8082/v1/add")
s3 = BaseService(id="s3", endpoint="http://localhost:8083/v1/add")
s4 = BaseService(id="s4", endpoint="http://localhost:8084/v1/add")
s5 = BaseService(id="s5", endpoint="http://localhost:8085/v1/add")
service_builder.add(s1).add(s2).add(s3).add(s4).add(s5)
service_builder.flow_to(s1, s2)
service_builder.flow_to(s5, s2)
service_builder.flow_to(s2, s3)
service_builder.flow_to(s2, s4)
service_builder.flow_to(s3, s4)

How has this PR been tested?

local test

Dependency Change?

None