minor refactor in platform driver's get_resource_capabilities, with new option to retrieve actual capability enum class attributes (instead of the corresp values, which continues to be the default behaviour). This is help make the mission executive more general.
add get_platform_driver_event_class to PlatformDriver
Merge pull request #2153 from carueda/pa_mx_driver_capabilities

minor refactor in platform driver's get_resource_capabilities