Restructure `dimos/` files

The project has grown in some random ways and it would be helpful to logically reorder some of the directories in dimos/.

This will be quite disruptive, but I think necessary (and better now than later).

First PR:

• learning to imitation (it's about imitation learning so we should probably narrow it down)
• core/tests to core/demos
• agents/{testing.py,agent_test_runner.py,vlm_stream_tester.py} to agents/testing/

Some proposals (all relative to /dimos/):

• memory2 to memory
• robot/cli and utils/cli to cli
• all the blueprint specifications to blueprints including all_blueprints.py and related
• mapping/utils/cli to mapping/clior cli
• spec/utils.pyto core/spec.py (this contains the is_spec stuff used in blueprints/modules)
• navigation/visual/query.py and navigation/bbox_navigation.py to agent/skills
• models/qwen to models/vl/qwen (like the others)
• perception/experimental/temporal_memory to experimental/temporal_memory
• perception/object_tracker.py (and \_2d/\_3d) to perception/tracking
• perception/{spatial_perception.py,spatial_vector_db.py,visual_memory.py} into perception/spatial_memory/
• delete msgs/sensor_msgs/image_impls/AbstractImage.py (can't, it's used by data/unitree_go2_bigoffice/video)
• skills folded into the rest of the skills in agent/skills
• agents/system_prompt.py to robot/unitree/go2/system_prompt.py
• utils/docs/doclinks.py to cli/docklinks.py

Other:

• I think we should break up protocol. You wouldn't have a directory called classes or functions. Things should be grouped by their area, not what they are. It's especially not a good idea since protocol doesnt just contain Protocols, but also implementations in protocol/pubsub/impl and benchmarks
• Pubsub stuff should be moved into core/pubsub(out of protocol)
• Move transport stuff to core/transport(e.g. core/transport.py, core/transport_factory.py

Please expand, if you have suggestions.

• If you disagree with something
  • Please add a sub point like this. If you feel very strongly that something is bad, please cross off the item

Ideally, if project is structured really well, there wouldn't be so many cross project imports. This is our current project (dirs below 10000 lines are collapsed)

Synced from DIM-1181 by paul.nechifor

Start by reviewing the proposed moves under dimos/, especially protocol, pubsub, transport, and agent/skills, then trace the cross-project imports affected by each. The work is done when the directory structure has an agreed design and the affected imports and references are updated consistently.