Support environment variables for Dapr Sidekick settings

[badgeratu]

Describe the feature

It should be possible to use environment variables to configure some/all of the Dapr Sidekick settings such that any environment variable prefixed with DAPRSIDEKICK_ (say) could be read on startup and mapped to configuration values.

As an example, it may be desirable to disable Dapr Sidekick entirely in a container deployed scenario, such that Sidekick is used for a seamless development and debugging experience in Visual Studio but on deployment is disabled in containers. This can currently be achieved by modifying the appsettings.json to set the top-level Enabled setting to false:

{
  "Dapr": {
    "Enabled": false
  }
 }

However some orchestration platforms (or docker compose) might prefer to set an environment variable such as DAPRSIDEKICK_ENABLED=false to achieve the same thing.