Add PPU backend support

[guozixu2001]

Motivation

This pull request introduces backend support for PPU devices in lmdeploy.

Modification

This PR implements the necessary components to integrate PPU as a new device backend. The key changes include:

1. Added PpuOpsBackend: A new backend implementation (lmdeploy/pytorch/backends/dlinfer/ppu/op_backend.py) is introduced to handle PPU-specific operations.
2. System-wide Integration:
   • Added 'ppu' as a valid device option in the command-line interface (cli/utils.py), engine configuration (messages.py), and utility functions (utils.py).
   • Updated the backend selector (selector.py) and kernel dispatcher (dispatcher.py) to recognize and load the PpuOpsBackend when the device is set to 'ppu'.

BC-breaking (Optional)

No.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit tests to ensure the correctness.
3. If the modification has a dependency on downstream projects of a newer version, this PR should be tested with all supported versions of downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[lvhan028]

May resolve the conflict.
Could you kindly provide the user guide as well?

[grimoire]

LGTM