Port subsystem development enhancements from wildfly-clustering-common to wildfly-core

wildfly-clustering-common contains many abstractions for simplifying subsystem development. Given that many non-clustering subsystem depend on this module in order to use these abstractions, it's clear that most of this module should be ported and integrated into wildfly-core.

The primary pieces of functionality are:

• ServiceBuilder decorator that transparently adds async behavior to Service start/stop
• Abstractions that simplifying cross-subsystem capability dependencies and default-aware resolution
  + Integrate into RuntimeCapability and CapabilityServiceBuilder
• Interfaces and ResourceDefinition subclasses for streamlining resource registration
• Resource implementation supporting dynamic child resources
• Service configurator interfaces that encapsulate service installation for use by multiple operation handlers
• Runtime handler interface and implementations that allow the use of entirely generic add/remove operation handlers
• Abstractions for implementing metrics and runtime operations that rely on service values
• Generic extension implementations that leverage streamlined resource registration