Add Dapr Secret Store extension

[Jakob-k]

Background and Motivation

I want to define my Dapr dependencies in my application code as much as possible, instead of relying on various yaml files.
PubSub and StateStore is already supported (to an extend).

Proposed API

I would like to use something like:

var secretStore = builder.AddDaprSecretStore("secrets", new DaprSideCarOptions
{
LokalPath = "../components/secretstore"
});

[FullStackChef]

This should be addressed by CommunityToolkit/Aspire#460