Merge support for mash

[robwoolley]

The mash tool (https://github.com/[robwoolley/mash](https://github.com/robwoolley/mash) inherits mash_generated.bbclass

Integrate https://github.com/robwoolley/meta-ros/blob/spaceros-preview/meta-ros-common/classes/ros_generate_generated.bbclass as mash_generated.bbclass replacing ros-generate with mash-generate, ROS_GENERATE_GENERATED, with MASH_GENERATED, and ROS_GENERATE_GENERATED_BUILDTOOLS with MASH_GENERATED_BUILDTOOLS.

[robwoolley]

This is the commit with the old tool name: 1b69396