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/create-payload-index/simple-keyword/csharp.cs

@@ -0,0 +1,14 @@
+using Qdrant.Client;
+
+public class Snippet
+{
+	public static async Task Run()
+	{
+		var client = new QdrantClient("localhost", 6334);
+
+		await client.CreatePayloadIndexAsync(
+		    collectionName: "{collection_name}",
+		    fieldName: "name_of_the_field_to_index"
+		);
+	}
+}

qdrant-landing/content/documentation/headless/snippets/create-payload-index/simple-keyword/go.go

@@ -0,0 +1,20 @@
+package snippet
+
+import (
+    "context"
+
+    "github.com/qdrant/go-client/qdrant"
+)
+
+func Main() {
+	client, err := qdrant.NewClient(&qdrant.Config{
+	    Host: "localhost",
+	    Port: 6334,
+	})
+
+	client.CreateFieldIndex(context.Background(), &qdrant.CreateFieldIndexCollection{
+	    CollectionName: "{collection_name}",
+	    FieldName:      "name_of_the_field_to_index",
+	    FieldType:      qdrant.FieldType_FieldTypeKeyword.Enum(),
+	})
+}

qdrant-landing/content/documentation/headless/snippets/create-payload-index/simple-keyword/java.java

@@ -0,0 +1,16 @@
+package com.example.snippets_amalgamation;
+
+import io.qdrant.client.grpc.Collections.PayloadSchemaType;
+
+public class Snippet {
+        public static void run() throws Exception {
+                client.createPayloadIndexAsync(
+                    "{collection_name}",
+                    "name_of_the_field_to_index",
+                    PayloadSchemaType.Keyword,
+                    null,
+                    true,
+                    null,
+                    null);
+        }
+}

qdrant-landing/content/documentation/headless/snippets/create-payload-index/simple-keyword/python.py

@@ -0,0 +1,9 @@
+from qdrant_client import QdrantClient  # @hide
+
+client = QdrantClient(url="http://localhost:6333")  # @hide
+
+client.create_payload_index(
+    collection_name="{collection_name}",
+    field_name="name_of_the_field_to_index",
+    field_schema="keyword",
+)

qdrant-landing/content/documentation/headless/snippets/create-payload-index/simple-keyword/rust.rs

@@ -0,0 +1,16 @@
+use qdrant_client::qdrant::{CreateFieldIndexCollectionBuilder, FieldType};
+
+pub async fn main() -> anyhow::Result<()> {
+    client
+        .create_field_index(
+            CreateFieldIndexCollectionBuilder::new(
+                "{collection_name}",
+                "name_of_the_field_to_index",
+                FieldType::Keyword,
+            )
+            .wait(true),
+        )
+        .await?;
+
+    Ok(())
+}

qdrant-landing/content/documentation/headless/snippets/create-payload-index/simple-keyword/typescript.ts

@@ -0,0 +1,8 @@
+import { QdrantClient } from "@qdrant/js-client-rest"; // @hide
+
+const client = new QdrantClient({ host: "localhost", port: 6333 }); // @hide
+
+client.createPayloadIndex("{collection_name}", {
+  field_name: "name_of_the_field_to_index",
+  field_schema: "keyword",
+});