Maven plugin for Helidon Service Inject

[tomas-langer]

Maven plugin that:

• generates application binding class (bindings for injection points)
• generates main class (registration of descriptor instances to InjectConfig that disables bootstrap service discovery)
• updated tests

To see what happens, build the project with -Ptests, and check directory:
service/tests/inject/toolbox/target/generated-sources/annotations/io/helidon/service/tests/inject/toolbox

See ApplicationMain and Injection__Binding classes.