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/strict-mode/max-payload-index-count/go.go

@@ -0,0 +1,22 @@
+package snippet
+
+import (
+  "context"
+
+  "github.com/qdrant/go-client/qdrant"
+)
+
+func Main() {
+	client, err := qdrant.NewClient(&qdrant.Config{
+	  Host: "localhost",
+	  Port: 6334,
+	})
+
+	client.CreateCollection(context.Background(), &qdrant.CreateCollection{
+	  CollectionName: "{collection_name}",
+	  StrictModeConfig: &qdrant.StrictModeConfig{
+	    Enabled: qdrant.PtrOf(true),
+	    MaxPayloadIndexCount: qdrant.PtrOf(uint64(10)),
+	  },
+	})
+}