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/modules/__init__.py

@@ -0,0 +1,19 @@
+# PEP 585に従う - 標準コレクションでの型ヒント
+# https://peps.python.org/pep-0585/
+from __future__ import annotations
+
+# 共通ライブラリをここでインポートして、`from module import *`でコードを簡潔にする
+from .list_node import (
+    ListNode,
+    list_to_linked_list,
+    linked_list_to_list,
+)
+from .tree_node import TreeNode, list_to_tree, tree_to_list
+from .vertex import Vertex, vals_to_vets, vets_to_vals
+from .print_util import (
+    print_matrix,
+    print_linked_list,
+    print_tree,
+    print_dict,
+    print_heap,
+)