Adds support for namespaces to TurtleBot4Navigator.

[Pbopbo]

Description

Currently it is not possible to use the Turtlebot4Navigator while also using the concept of namespaces.
The Turtlebot4Navigator class inherits form the BasicNavigator class.
The BasicNavigators class __init fucntion has the signature:

def __init__(self, node_name='basic_navigator', namespace=''):

In this PR the namespace parameter is exposed in the __init function of the Turtlebot4Navigator.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

I ran the tutorial code given at https://turtlebot.github.io/turtlebot4-user-manual/tutorials/turtlebot4_navigator.html#navigate-to-pose which previously failed previously because some topics could not be found. (Because their names are prefixed by the namespace).
With this change the library works fine.

Checklist

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation

[hilary-luo]

Note that although this updates Turtlebot4Navigator to receive a namespace, users must still manually pass the namespace when creating the BasicNavigator object which requires modification of the individual tutorial codes. No documentation has been updated at this point to indicate that this is an option.

[hilary-luo]

FYI @civerachb-cpr for Jazzy

[civerachb-cpr]

Cherry-picked into jazzy