Record a warning for sonarqube when bytecode of dependencies is not provided

This ticket will be handled by the Platform team which will submit a PR to the language team.

Currently, when bytecode of dependencies is not provided, a warn message is added to the scanner logs.

The point of this ticket is to leverage the new plugin API which allows to record warnings that will available to be read right from SQ's UI for any user with browse permission on the project.

The warning message should be the following:

Bytecode of dependencies was not provided for analysis of source files, you might end up with less precise results. Bytecode can be provided using "sonar.java.libraries property"

Implementation notes

This work depends on new features in the SonarQube API. It can be merged after the API changes are part of a milestone / stable release (ETA Sep 28).
Update: new expected ETA: Oct 10