Add default component for Secret Store

[artursouza]

Describe the proposal

dapr init should also create a default component for secret store, it can be from ENV

Release Note

RELEASE NOTE:

[mukundansundar]

Should we default to adding an env var secret store? That introduces the case where all env vars are available for users to use.
I am thinking about scenarios where self hosted mode is used not for dev purpose alone.

@artursouza thoughts?