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.

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

ja/codes/python/test_all.py

@@ -0,0 +1,33 @@
+import os
+import glob
+import subprocess
+
+env = os.environ.copy()
+env["PYTHONIOENCODING"] = "utf-8"
+
+if __name__ == "__main__":
+    # ソースコードファイルを検索
+    src_paths = sorted(glob.glob("ja/codes/python/chapter_*/*.py"))
+    errors = []
+
+    # python コードを実行
+    for src_path in src_paths:
+        process = subprocess.Popen(
+            ["python", src_path],
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            text=True,
+            env=env,
+            encoding='utf-8'
+        )
+        # プロセスの完了を待ち、出力とエラーメッセージを取得
+        stdout, stderr = process.communicate()
+        # 終了ステータスをチェック
+        exit_status = process.returncode
+        if exit_status != 0:
+            errors.append(stderr)
+
+    print(f"{len(src_paths)} ファイルをテストしました")
+    print(f"{len(errors)} ファイルで例外が見つかりました")
+    if len(errors) > 0:
+        raise RuntimeError("\n\n".join(errors))