docs: add Japanese translate documents (#1812)

* docs: add Japanese documents (`ja/docs`)

* docs: add Japanese documents (`ja/codes`)

* docs: add Japanese documents

* Remove pythontutor blocks in ja/

* Add an empty at the end of each markdown file.

* Add the missing figures (use the English version temporarily).

* Add index.md for Japanese version.

* Add index.html for Japanese version.

* Add missing index.assets

* Fix backtracking_algorithm.md for Japanese version.

* Add avatar_eltociear.jpg. Fix image links on the Japanese landing page.

* Add the Japanese banner.

---------

Co-authored-by: krahets <krahets@163.com>

ja/codes/java/chapter_stack_and_queue/deque.java

@@ -0,0 +1,46 @@
+/**
+ * File: deque.java
+ * Created Time: 2022-11-25
+ * Author: krahets (krahets@163.com)
+ */
+
+package chapter_stack_and_queue;
+
+import java.util.*;
+
+public class deque {
+    public static void main(String[] args) {
+        /* 両端キューを初期化 */
+        Deque<Integer> deque = new LinkedList<>();
+        deque.offerLast(3);
+        deque.offerLast(2);
+        deque.offerLast(5);
+        System.out.println("両端キュー deque = " + deque);
+
+        /* 要素へのアクセス */
+        int peekFirst = deque.peekFirst();
+        System.out.println("先頭要素 peekFirst = " + peekFirst);
+        int peekLast = deque.peekLast();
+        System.out.println("末尾要素 peekLast = " + peekLast);
+
+        /* 要素のエンキュー */
+        deque.offerLast(4);
+        System.out.println("要素4を末尾にエンキュー、deque = " + deque);
+        deque.offerFirst(1);
+        System.out.println("要素1を先頭にエンキュー、deque = " + deque);
+
+        /* 要素のデキュー */
+        int popLast = deque.pollLast();
+        System.out.println("両端キュー末尾要素 = " + popLast + "、末尾からデキュー後 " + deque);
+        int popFirst = deque.pollFirst();
+        System.out.println("両端キュー先頭要素 = " + popFirst + "、先頭からデキュー後 " + deque);
+
+        /* 両端キューの長さを取得 */
+        int size = deque.size();
+        System.out.println("両端キューの長さ size = " + size);
+
+        /* 両端キューが空かどうかを判定 */
+        boolean isEmpty = deque.isEmpty();
+        System.out.println("両端キューが空か = " + isEmpty);
+    }
+}