PropertiesLauncher can now be used to run an executable jar, and by
default it will pick up nested archives in lib/ (where the Boot
tools puts them). User can provide loader.path (colon-separated)
to change the nested path.
[#58837492] [bs-330] Add tooling for PropertiesLauncher
Update RunMojo to include an @Execute annotation. Allows the use of
`mvn spring-boot:run` without having to compile/package first. Now a
command like `mvn clean spring-boot:run` works.
The phase for @Execute annotation is along the lines of what is used
for the `jetty:run` plugin.