`dapr init` should initialize a local secret store

## Describe the proposal

In addition to state and pub/sub components, `dapr init` should initialize a secret store component backed by a local JSON file, located in the default component directory.

Then in the docs we should always reference the secret store via secretRef instead of having credentials in plaintext.

#742 captures the ability to add secrets to this local secret store

## Release Note

RELEASE NOTE: **ADD** local secret store component with `dapr init`