[example] update opt example using booster api (#3918)

examples/language/opt/run_demo.sh

@@ -0,0 +1,44 @@
+set -xe
+pip install -r requirements.txt
+
+# model name or path
+MODEL="facebook/opt-350m"
+
+# path for saving model
+OUTPUT_PATH="./output_model.bin"
+
+# plugin(training strategy)
+# can only be one of "torch_ddp"/"torch_ddp_fp16"/"low_level_zero"/"gemini"
+PLUGIN="gemini"
+
+# number of gpus to use
+GPUNUM=4
+
+# batch size per gpu
+BS=16
+
+# learning rate
+LR="5e-5"
+
+# number of epoch
+EPOCH=10
+
+# weight decay
+WEIGHT_DECAY=0.01
+
+# ratio of warmup steps
+WARMUP_RATIO=0.1
+
+# run the script for demo
+torchrun \
+  --standalone \
+  --nproc_per_node ${GPUNUM} \
+  opt_train_demo.py \
+  --model_name_or_path ${MODEL} \
+  --output_path ${OUTPUT_PATH} \
+  --plugin ${PLUGIN} \
+  --batch_size ${BS} \
+  --num_epoch ${EPOCH} \
+  --learning_rate ${LR} \
+  --weight_decay ${WEIGHT_DECAY} \
+  --warmup_ratio ${WARMUP_RATIO}