Support to set applicationName and agentId by application

[quaff]

Which module is your feature request related to?
Agent

Is your feature request related to a problem?
Typically application server should be identical for every application and instance, this is convenient to duplicate instances, especially useful for container runtime like k8s.
currently applicationName and agentId must be configured by VM arguments, runtime configuration is unique per instance.

Describe the solution you'd like
Defer getting applicationName and agentId from system property, allow application set "pinpoint.applicationName" and "pinpoint.agentId" via System::setProperty, application can reuse existed property such as "application.name" of spring boot, and dynamic generated agentId which cannot be predicated in VM args.