ROS topic names ignore namespace configuration when spawning multiple robots of the same model

[nahueespinosa]

Hi! There seems to be a bug in the way ROS topic names are loaded in various plugins.

How to reproduce

Add a laser plugin to a robot model:

plugins:
  - type: Laser
    name: laser_front
    frame: laser_front
    topic: scan2
    body: base2
    broadcast_tf: true
    origin: [0.28, 0, 0]
    range: 20
    angle: {min: -2.356194490192345, max: 2.356194490192345, increment: 0.004363323129985824}
    noise_std_dev: 0.05
    update_rate: 40

Launch a flatland_server node with the following world configuration file and see how both robots publish on the same topic (/scan2):

models:
  - name: turtlebot1
    namespace: robot1
    pose: [0, 0, 0]
    model: "turtlebot.model.yaml"
    
  - name: turtlebot2
    namespace: robot2
    pose: [0, 1, 0]
    model: "turtlebot.model.yaml"

Cause

In flatland_server/src/model.cpp there is a function called NameSpaceTopic used to prepend the namespace to the topic name before creating a publisher.

Currently, this is only used in bool_sensor.cpp but it should probably be added to other plugins, like laser.cpp.