Ignore/include properties in application.properties depending on test scope

[angelozerr]

According @fbricon:

We need to consider the "test" flag of the source directory the application.properties is coming from.

• if no "test" flag, then key/value pairs from test dependencies should not be considered to be returned to the client (edited)

• if "test" flag is on, then key/value pairs from test dependencies should also be returned (edited)

As a use case, imagine an application.properties in src/test/resources, that would be able to use a specific test database (from a quarkus extension available in the test scope), in order to override a production DB defined in src/main/resources/application.properties