[RFC] DeepSeekV4 Support

[matthewygf]

Is your feature request related to a problem? Please describe.
Support DSV4 on LMCache-Ascend

Describe the solution you'd like

• Might also depends on upstream.

Describe alternatives you've considered
N/A

Additional context
N/A

[matthewygf]

#246 We currently have DSV4 support in a separate PR, going forward this will become a separate branch as we are migrating to MP mode, with the aim to merge in the main upstream repo