Fix node field calls in 'sim_bridge/unity_bridge.py'

[Alb33rt]

Problem

As we know, ROS2 utilizes node classes for defining abstract "nodes" in a ROS Graph. This paradigm shift is in contrast to ROS1's simple and pure function definitions and calls. Because of this, nodes have attributes/fields that would otherwise be considered "global" in the context of ROS1.

In unity_bridge.py of the package sim_bridge. Fix the function calls so that the nodes actually work. The scoped variables within each function should be talking to each other. For example, add a self. before each attribute so that the variables become class attributes instead.

Examples

Example compare and contrast between ROS2 (left) and ROS1 (right):

Example code snippet where problem occurs: