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/query/rust.rs

@@ -0,0 +1,23 @@
+use qdrant_client::{
+    Qdrant, QdrantError,
+    qdrant::{Document, Query, QueryPointsBuilder},
+};
+
+pub async fn main() -> anyhow::Result<()> {
+    let client = Qdrant::from_url("<your-qdrant-url>").build().unwrap();
+
+    client
+        .query(
+            QueryPointsBuilder::new("{collection_name}")
+                .query(Query::new_nearest(Document {
+                    text: "How to bake cookies?".into(),
+                    model: "qdrant/bm25".into(),
+                    ..Default::default()
+                }))
+                .using("my-bm25-vector")
+                .build(),
+        )
+        .await?;
+
+    Ok(())
+}