Introduce Planner Coordinate Frame

# Feature Request

To introduce a Planner Coordinate Frame. This reduced ambiguity when defining planning targets, specifying planning group, and how tools are attached to robots.

## Details

After multiple sessions of brainstorm with @gonzalocasas, we realized there is an ambiguity in compas_fab regarding the behavior of how planning groups are handled. Planning groups, as an essential concept for robot motion planning, defines which joints can be moved by emotion planner.

Typically the planning groups are defined and extracted as a read-only attribute from an SRDF file. At the moment, compas_fab do not provide support for users to edit SRDF or the definition of planning groups. The rationale of this is because in the current workflow of using the ROS Planning backend, the SRDF is already embedded in the Docker image file. Many of the embedded SRDF are provided by open repos (such as by ROS-Industrial) are not maintained by us.

more coming...