Consider splitting `@Config`, `@ConfigDefault`, and `Task` to a separate artifact, such as `embulk-util-config-task`

[dmikurube]

Some other util librarires sometimes want to prepare a predefined Task interface, but they have to depend on the entire embulk-util-config to do that. The dependency involves Jackson collaterally -- which takes developers closer to the dependency hell.

If another util library can only depend on @Config, @ConfigDefault, and Task, it'd be helpful.

[dmikurube]

For Java modularity, they may have to be in a separate Java package: such as package org.embulk.util.config.task. Therefore, embulk-util-config has to be able to process both org.embulk.util.config.Task and org.embulk.util.config.task.Task at the same time.

org.embulk.util.config.Task may be just @Deprecated, though.