### What problem does this PR solve?
1. Supports stream and non-stream chat
2. Supports think and non-think chat
3. List supported models from DeepSeek service. (This command can be
used to verify the API validity)
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
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Signed-off-by: Jin Hai <haijin.chn@gmail.com>