NASA Challenge_[franklinselva]_[IsaacSim Integration for Canadarm2 demo]

[franklinselva]

The purpose of this PR is to provide IsaacSim Integration with the demos repository.

Depends on #31
Blocked by space-ros/simulation#21

Merge queue 2

The main changes in this PR include,

• The demo repository of canadarm2 is restructured to the diagram represented below
• Both the simulation interfaces are supported (gazebosim and isaacsim). This allows the demos to be reproducible in both the interfaces
• The use of Makefile is simpler for spinning off the demos in both the simulations.
• The documentation to run demos in both the environments has been updated

graph LR
    A[GazeboSim] <--> B[Ignition ROS2]
    B <--ROS2 control--> C[Common Package]
    C <--> D[Demo Packages]
    D <--> E[Space ROS2]

    C <--Isaac ROS2 Bridge--> F[Isaac Sim ROS2 Extension]
    F <--> G[Isaac Sim]


    subgraph Host Machine - GazeboSim
        A
        B
    end

    subgraph Host Machine - Isaac Sim
        F
        G
    end

    subgraph Space ROS Container
        C
        D
        E
    end

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Note for reviewers: This PR is not meant to be large and the blocker item needs to be merged first to tackle the problem.