Enable Speculative Mixtral on CPU

[Uxito-Ada]

Description

Speculative Mixtral on CPU, which is tested with mistralai/Mixtral-8x7B-Instruct-v0.1 and mistralai/Mixtral-8x7B-v0.1 on SPR.

1. Why the change?

as above

2. User API changes

no

3. Summary of the change

Enable CPU Speculative Mixtral

4. How to test?

• [ ] N/A
• [ ] Unit test
• [x] Application test
• [x] Document test
• [ ] ...