Load all the plugins in the bnd config properly instead of only the last one

[dylan-reniers-digitalum]

Description

Use separate properties for the different plugins in the BND tools config, so all plugins are properly loaded and not overwritten so only the last one is used.

Related Issue

Motivation and Context

Currently only the last plugin definition is used, since it overwrites any previous plugins in the config.

How Has This Been Tested?

Verified by doing maven builds and comparing the output of the OSGi manifest, to see which headers are present. Before only the Sling-Model-Classes header was present, now also the Sling-ContextAware-Configuration-Classes.

Screenshots (if appropriate):

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] I have signed the Adobe Open Source CLA.
• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.