Use clustered-object-pool cluster-specific configuration

[bbottema]

Pull in clustered-object-pool support for cluster-specific defaults so clustered SMTP pools can preserve different behavior per cluster key instead of relying only on one global config.

Usage:

SmtpClusterConfig<UUID> defaults = new SmtpClusterConfig<>();
SmtpConnectionPoolClustered<UUID> pool = new SmtpConnectionPoolClustered<>(defaults);

SmtpClusterConfig<UUID> constrainedCluster = new SmtpClusterConfig<>();
constrainedCluster.getConfigBuilder()
    .defaultCorePoolSize(0)
    .defaultMaxPoolSize(1)
    .claimTimeout(new Timeout(30, TimeUnit.SECONDS));

pool.registerResourceCluster(constrainedClusterKey, constrainedCluster.getConfigBuilder().build());
pool.registerResourcePool(new ResourceClusterAndPoolKey<>(constrainedClusterKey, sessionServerA));

Supports bbottema/simple-java-mail#565.

[bbottema]

Implemented for the 3.0.1 milestone.

smtp-connection-pool now depends on clustered-object-pool 4.0.1, so SmtpConnectionPoolClustered inherits cluster-specific defaults through registerResourceCluster(...).

This supports bbottema/simple-java-mail#565.