Automated snippet conversion by scripts

These changes are purely mechanical to differentiate them from manual
fixes/adjustments made in the next commit.
This results in broken code as some snippets contain errors.

Made in four steps:
1. Run ./migrate-snippet.py that converts `.md` files to code files
   and perhaps adds missing lines under `// @hide` comments.
2. Sort Java imports.
3. Remove old `.md` files.
4. Run ./generate.md to produce `*/generated/*.md` files.

qdrant-landing/content/documentation/headless/snippets/inference/openai-upsert/python.py

@@ -0,0 +1,24 @@
+from qdrant_client import QdrantClient, models
+
+client = QdrantClient(
+    url="https://xyz-example.qdrant.io:6333", 
+    api_key="<your-api-key>", 
+    cloud_inference=True
+)
+
+client.upsert(
+    collection_name="{collection_name}",
+    points=[
+        models.PointStruct(
+            id=1,
+            vector=models.Document(
+                text="Recipe for baking chocolate chip cookies",
+                model="openai/text-embedding-3-large",
+                options={
+                    "openai-api-key": "<your_openai_api_key>",
+                    "dimensions": 512
+                }
+            )
+        )
+    ]
+)