This adds a scaling factor between 0 and 1 to the JTC so that the trajectory
time inside the controller is extended respectively. A value of 0.5 means
that trajectory execution will take twice as long as the trajectory states.

The scaling factor itself is read from the hardware for now.

Co-authored-by: Christoph Fröhlich <[email protected]>

This avoids writing the explicit conversion by hand

Internally that basically does:
static_cast<rcl_duration_value_t>(static_cast<long double>(rcl_duration_.nanoseconds) * scale_ld)

…etting

of scaling factor

Co-authored-by: Manuel M <[email protected]>