[java-sdk] Create Dapr's HTTP Client

[artursouza]

NEW SCOPE:
Manually create http client for Dapr's APIs.

OLD SCOPE:

• Auto-generate http client from Dapr's OpenAPI definition (https://swagger.io/specification/)
• If needed, create OpenAPI definition in Dapr/dapr to seed auto-generation for any language.

[amanbha]

Linking to dapr/dapr#16

For now, we can handcraft the http calls as we have few http calls. Autogenerated ones will need to be wrapped.

[artursouza]

It seems that we don't have the OpenAPI specs ready to complete this task.

[artursouza]

I have changed the scope of this task to not use the auto-generated version since we don't have service API specs for that yet. It can be simply be manually created right now.

[mestizoLopez]

Can you assign me please?