[tests] relocate core integration tests (#11146)

* relocate core integration tests

* add sys.path context manager

* cleanup

* try

* try2

* fix path

* doc

* style

* add dep

* add 2 more deps

tests/deepspeed/ds_config_zero2.json

@@ -0,0 +1,43 @@
+{
+    "fp16": {
+        "enabled": true,
+        "loss_scale": 0,
+        "loss_scale_window": 1000,
+        "initial_scale_power": 16,
+        "hysteresis": 2,
+        "min_loss_scale": 1
+    },
+
+    "zero_optimization": {
+        "stage": 2,
+        "allgather_partitions": true,
+        "allgather_bucket_size": 2e8,
+        "overlap_comm": true,
+        "reduce_scatter": true,
+        "reduce_bucket_size": 2e8,
+        "contiguous_gradients": true,
+        "cpu_offload": true
+    },
+
+    "optimizer": {
+        "type": "AdamW",
+        "params": {
+            "lr": 3e-5,
+            "betas": [0.8, 0.999],
+            "eps": 1e-8,
+            "weight_decay": 3e-7
+        }
+    },
+
+    "scheduler": {
+        "type": "WarmupLR",
+        "params": {
+            "warmup_min_lr": 0,
+            "warmup_max_lr": 3e-5,
+            "warmup_num_steps": 500
+        }
+    },
+
+    "steps_per_print": 2000,
+    "wall_clock_breakdown": false
+}