[Gemini] add unitests to check gemini correctness (#2015)

tests/components_to_test/utils/executor.py

@@ -0,0 +1,15 @@
+import torch
+
+
+def run_fwd_bwd(model, data, label, criterion, enable_autocast=False, use_init_ctx=False):
+    with torch.cuda.amp.autocast(enabled=enable_autocast):
+        if criterion:
+            y = model(data)
+            loss = criterion(y, label)
+        else:
+            loss = model(data, label)
+        loss = loss.float()
+    if use_init_ctx:
+        model.backward(loss)
+    else:
+        loss.backward()