Externalise path of Eclipse Equinox Launcher jar

[lczupryn]

****What's this Pull request about? Externalise path of Eclipse Equinox Launcher jar - path as a maven property "eclipse.plugins". Having externalized eclipse plugins path helps during the maven test phase executed in a docker container with bwce-runtime base (CI steps). ****Which Issue(s) this Pull Request will fix? No issue - new feature needed for CI/CD pipeline

****Does this pull request maintain backward compatibility? Yes - if the "eclipse.plugins" property is not defined in a project the default path would be applied

****How this pull request has been tested? -with/without new property in a local environment with a studio -with/without new property in docker container without studio/ just equinox launcher jar file

****Screenshots (if appropriate)

Screenshot(s) of the change

****Any background context or comments you want to provide?

Needed for CI/CD pipeline - Test Unit executed in a docker container (bwce-runtime image) + equinox launcher jar