Improve Redis IDistributedCache integration

[sebastienros]

The current implementation doesn't support multiple IDistributedCache instances to be registered, either using dedicated Redis instances or a shared one with prefixes.

This is due to how the IDistributedCache is used in aspnetcore and also how the extension method to register the service is designed. This is confusing users as reported here and from internal usage.

dotnet/docs-aspire#2625

The suggestion is to change the current API to support these scenarios.

The following usage would then be possible:

builder.AddRedisDistributedCache("redis1");
builder.AddKeyedRedisDistributedCache(name: "redis2");
builder.AddKeyedRedisDistributedCache(name: "redis2", serviceKey: "redis3");

This would result in:

• a non-keyed IDistributedCache service registration using the Redis resource redis1
• a keyed IDistributedCache service using a different Redis resource redis2, and no key prefix
• a keyed IDistributedCache service using the same Redis resource redis2, but with the "redis3" service key, and the prefix "redis3" for its keys

Service resolution would be done like so:

app.MapGet("/cache1", async (IDistributedCache cache) => { ... });
app.MapGet("/cache2", async ([FromKeyedServices("redis2")] IDistributedCache cache) => { ... });
app.MapGet("/cache3", async ([FromKeyedServices("redis3")] IDistributedCache cache) => { ... });

[eerhardt]

and the prefix "redis3" for its keys

I think the prefix needs to be a separate concern from the service key. Probably the ability to configure the RedisCacheOptions is necessary.

[eerhardt]

I also half wonder if we should make "keyed" distributed caches more of an official support in dotnet/aspnetcore. This isn't criticial to make the experience better in Aspire, but just a thought.