Consinder adding WithConfBindMount method for configured conf directory for Redis resource

The Redis container image supports setting a custom conf directory so that a custom `redis.conf` file can be used to initialize the Redis server. We should consider adding an extension method to make it easy to configure this, e.g.:

```csharp
///
/// Adds a bind mount for the conf folder to a Redis container resource.
///
/// The resource builder.
/// The source directory on the host containing the redis.conf file to mount into the container.
/// The .
public static IResourceBuilder WithConfBindMount(this IResourceBuilder builder, string source)
=> builder.WithBindMount(source, "/usr/local/etc/redis", isReadOnly: false)
.WithArgs("/usr/local/etc/redis/redis.conf");
```