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/retrieve-points/simple/generated/csharp.md

@@ -0,0 +1,12 @@
+```csharp
+using Qdrant.Client;
+
+var client = new QdrantClient("localhost", 6334);
+
+await client.RetrieveAsync(
+	collectionName: "{collection_name}",
+	ids: [0, 30, 100],
+	withPayload: false,
+	withVectors: false
+);
+```

qdrant-landing/content/documentation/headless/snippets/retrieve-points/simple/generated/go.md

@@ -0,0 +1,19 @@
+```go
+import (
+	"context"
+
+	"github.com/qdrant/go-client/qdrant"
+)
+
+client, err := qdrant.NewClient(&qdrant.Config{
+	Host: "localhost",
+	Port: 6334,
+})
+
+client.Get(context.Background(), &qdrant.GetPoints{
+	CollectionName: "{collection_name}",
+	Ids: []*qdrant.PointId{
+		qdrant.NewIDNum(0), qdrant.NewIDNum(3), qdrant.NewIDNum(100),
+	},
+})
+```

qdrant-landing/content/documentation/headless/snippets/retrieve-points/simple/generated/java.md

@@ -0,0 +1,9 @@
+```java
+import static io.qdrant.client.PointIdFactory.id;
+
+import java.util.List;
+
+client
+    .retrieveAsync("{collection_name}", List.of(id(0), id(30), id(100)), false, false, null)
+    .get();
+```

qdrant-landing/content/documentation/headless/snippets/retrieve-points/simple/generated/python.md

@@ -0,0 +1,6 @@
+```python
+client.retrieve(
+    collection_name="{collection_name}",
+    ids=[0, 3, 100],
+)
+```

qdrant-landing/content/documentation/headless/snippets/retrieve-points/simple/generated/rust.md

@@ -0,0 +1,10 @@
+```rust
+use qdrant_client::qdrant::GetPointsBuilder;
+
+client
+    .get_points(GetPointsBuilder::new(
+        "{collection_name}",
+        vec![0.into(), 30.into(), 100.into()],
+    ))
+    .await?;
+```

qdrant-landing/content/documentation/headless/snippets/retrieve-points/simple/generated/typescript.md

@@ -0,0 +1,5 @@
+```typescript
+client.retrieve("{collection_name}", {
+  ids: [0, 3, 100],
+});
+```