Missing functionality for different default arm configurations

[KavitShah1998]

For resetting the arm, right now each environment (that uses the arm) is storing the arm initial configuration differently and resetting it inside its own implementation of reset method.

While this is good, it blocks the dev from reusing such resets in cases where envs are not to be used (eg : while using BD APIs)

Thus is would make more sense to create default configurations (for stow, carry, ready, etc) for spot-sim2real and have a wrapper method responsible for achieving those arm configuration.

The envs can further utilize this wrapper method. This will prevent a lot of code duplication and would be cleaner in the long run.