Correct "libcarla.command" namespace and allow from carla.command import ...

[Daraan]

Fixes #6414

Currently import carla.command or from carla.command import ... is not possible.

This will raise:

# command.py
      7 # pylint: disable=W0401
----> 8 from .libcarla.command import *

ModuleNotFoundError: No module named 'carla.libcarla.command'

This is because the command module is registered as libcarla.command in sys.modules. This is not really correct.

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This PR adjusts this:

• renames the module to carla.libcarla.command
• provides a duplicate carla.command that can be imported.

Note / Up to discussion:
This PR deletes command.py as otherwise carla.command is not carla.libcarla.command. Both modules would be equivalent but not the same. I think this is the cleaner option.

Alternatives

This PR:

• PRO: Compatibility is granted and extended to be more user friendly
• CON: Duplicate module in sys.modules

1. Instead of putting command into libcarla we could put it into carla directly without creating a duplicate carla.libcarla.command.
   • PRO: More user friendly, no duplication of the module in sys.modules.
   • CON: Not part of libcarla
2. Do not allow import carla.command and only from carla import command
   • PRO: No duplication in sys.modules
   • CON: Less user friendly

Where has this been tested?

• Platform(s): Ubuntu 22.04
• Python version(s): Python 3.10
• Unreal Engine version(s): 4.26

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This change is