Base fast motion sentry doesn't impact velocity control

[hello-binit]

Stretch Body's mobile base has a sentry that sets fast_motion_allowed based on the position of the arm. When the mass is low (i.e. the arm is tucked), the robot is more stable, and fast base motion is allowed. When the mass is high (i.e. the arm is up and extended), the robot is more unstable, and fast base motion is disabled. The sentry logic is:

stretch_body/body/stretch_body/base.py

Lines 529 to 538 in a97f03f

	if ((x_lift < self.params['sentry_max_velocity']['max_lift_height_m']) and
	(x_arm < self.params['sentry_max_velocity']['max_arm_extension_m']) and
	(x_wrist > self.params['sentry_max_velocity']['min_wrist_yaw_rad'])):
	if not self.fast_motion_allowed:
	self.logger.debug('Fast motion turned on')
	self.fast_motion_allowed = True
	else:
	if self.fast_motion_allowed:
	self.logger.debug('Fast motion turned off')
	self.fast_motion_allowed = False

However, the fast_motion_allowed variable is only used by Base.translate_by() and Base.rotate_by(), the two position control method available through Stretch Body. It is not used by Base.set_velocity(), the velocity control method. To complete the functionality intended by this safety feature, we should utilize the fast_motion_allowed variable within set_velocity(). Any duplication feature within GamepadTeleop should be removed.