[atom-vllm][DP/EP] enable DP/EP for atom-vllm

[zejunchen-zejun]

Enable DP and EP feature for below models:
For mori memory model, use MORI_SHMEM_MODE=ISOLATION to set the allocation behavior

• DeepSeek-FP8 DP8+EP8

Tasks	Version	Filter	n-shot	Metric		Value		Stderr
gsm8k	3	flexible-extract	3	exact_match	↑	0.9409	±	0.0065
		strict-match	3	exact_match	↑	0.9348	±	0.0068

• DeepSeek-FP8 TP8+EP8

Tasks	Version	Filter	n-shot	Metric		Value		Stderr
gsm8k	3	flexible-extract	3	exact_match	↑	0.9424	±	0.0064
		strict-match	3	exact_match	↑	0.9371	±	0.0067

• GPTOSS DP8

Tasks	Version	Filter	n-shot	Metric		Value		Stderr
gsm8k	3	flexible-extract	3	exact_match	↑	0.4352	±	0.0137
		strict-match	3	exact_match	↑	0.2441	±	0.0118

• GPTOSS DP8+EP8

Tasks	Version	Filter	n-shot	Metric		Value		Stderr
gsm8k	3	flexible-extract	3	exact_match	↑	0.4056	±	0.0135
		strict-match	3	exact_match	↑	0.2335	±	0.0117

• DeepSeek-MXFP4 DP8+EP8

• Kimi-K2 DP8+EP8

• Qwen3.5 FP8 DP8+EP8

Tasks	Version	Filter	n-shot	Metric		Value		Stderr
gsm8k	3	flexible-extract	3	exact_match	↑	0.8635	±	0.0095
		strict-match	3	exact_match	↑	0.8567	±	0.0097