examples/llm_server: add OpenAI-compatible LLM server (#20308) #14063

Job	Run time
Get changed files / get-changed-files	5s
CI run decision / decide	30s
check-all-cuda-builds	0s
test-executorch-cuda-build-${{ matrix.cuda-version }}	0s
test-cuda-pybind	0s
unittest-cuda	-1s
test-models-cuda	-1s
test-model-cuda-e2e	-1s
export-model-cuda-artifact	-1s
	31s

Provide feedback