Add support for properties (name-value pairs)

[msymons]

Schema 1.3 added support for properties (name-value pairs).

Now that Schema 1.3 is implemented in cyclonedx-maven-plugin as of v2.5.0, it would be useful for the plugin to support properties.

For maven projects in Dependency-Track, this enhancement would be the ying to the yang of Add support for namespaced CDX custom properties for DT features

[coderpatros]

I think this needs to be done in an ecosystem agnostic way. This is a bit like issue #129