Web app: add RTL support

Ref:

https://mui.com/material-ui/guides/right-to-left
https://m2.material.io/design/usability/bidirectionality.html

web/src/components/RTLCacheProvider.jsx

@@ -0,0 +1,22 @@
+import React from "react";
+
+import rtlPlugin from "stylis-plugin-rtl";
+import { CacheProvider } from "@emotion/react";
+import createCache from "@emotion/cache";
+import { prefixer } from "stylis";
+import { useTranslation } from "react-i18next";
+
+// https://mui.com/material-ui/guides/right-to-left
+
+const cacheRtl = createCache({
+  key: "muirtl",
+  stylisPlugins: [prefixer, rtlPlugin],
+});
+
+const RTLCacheProvider = ({ children }) => {
+  const { i18n } = useTranslation();
+
+  return i18n.dir() === "rtl" ? <CacheProvider value={cacheRtl}>{children}</CacheProvider> : children;
+};
+
+export default RTLCacheProvider;