Extending demo tests

[livanov93]

PR info:

• Depends on [GenericSystem] Add velocity-only mode in fake_components  ros2_control#540
• Add action test for jtc (velocity and position)
• Change parameters for forward_velocity_controller publisher
• Introduces use of disable_commands parameter for GenericSystem for simulating disconnected driver
• Add extended paramterization for JTCs

[olivier-stasse]

I propose to close this PR as it is clearly outdated wrt to the recent work.

[christophfroehlich]

I propose to close this PR as it is clearly outdated wrt to the recent work.

You are right. However, the disable command demo would be fine to include somewhere else.