Allow ServiceInstanceIdRegistry to manually register id selected by user

[swarmshine]

ServiceInstanceIdRegistry allows you to receive unique id from pool of generated ids on demand.
It is handy when you do not care about id numbers, acquired by your application instances:

Application A

fun main(){
  // 7
  val appId = registry.register("my-app")
}

Application B

fun main(){
  //13
  val appId = registry.register("my-app")
}

It is useful to have an opportunity to explicitly select which id which application instance will receive.
For example you have a cluster of applications of two types: red-apps and black-apps.
And to distinct them by id you can give them particular ids:

red-app #10     black-app #20
red-app #11     black-app #21
red-app #12
red-app #13

We can add new method to registry that allows user explicitly provide desirable identifier.
Then we can provide this id through command arguments during application startup.

java -jar red-app.jar --desirableId=10

fun main(args: String[]){
  val desirableId = idFromArguments(args)
  //10
  val appId = registry.register("red-app", desirableId)
}

This way we can control what id will be received by application during startup.
It is very handy during problem investigations: by id of application it is easily to detect a node.