adds translation support via i18n.js

Uses react-i18next library to provide APIs for translational
purposes.
Translation data is loaded from `src/locales/{{lng}}/translation.json`
and is accessed by dot notation.
The data can be translated in two ways:
1. In functional components, a method `t` can be instantiated using the
`useTranslation` method from rect-18next.
2. In class components, a method `t` can be accessed via props while
exporting the component with `withTranslation` method from react-i18next
library.

The syntax will look like `t('data.data')` or `this.props.t('data.data')`

Signed-off-by: Sudhanshu Gautam <me@sudhanshug.com>

src/locales/de/translation.json

@@ -0,0 +1,20 @@
+{
+    "title": "OpenWrt Firmware Selector Wizard",
+    "appIntro": {
+        "head": "Laden Sie die OpenWrt-Firmware für Ihr Gerät herunter!",
+        "para": "Bitte benutzen Sie den unten stehenden Eingang, um die Firmware für Ihr Gerät herunterzuladen!"
+    },
+    "components": {
+        "submit": "einreichen",
+        "changeLanguage": "Sprache ändern",
+        "select": {
+            "placeholder": "Wählen...",
+            "noOptions": "Keine Optionen"
+        }
+    },
+    "table": {
+        "model": "Modell",
+        "vendor": "Verkäufer",
+        "variant": "Variante"
+    }
+}

src/locales/en/translation.json

@@ -0,0 +1,20 @@
+{
+    "title": "OpenWrt Firmware Selector Wizard",
+    "appIntro": {
+        "head": "Download OpenWrt firmware for your device!",
+        "para": "Please use the input below to download firmware for your device!"
+    },
+    "components": {
+        "submit": "Submit",
+        "changeLanguage": "Change Language",
+        "select": {
+            "placeholder": "Select...",
+            "noOptions": "No options"
+        }
+    },
+    "table": {
+        "model": "Model",
+        "vendor": "Vendor",
+        "variant": "Variant"
+    }
+}