feat: localization (#196)

* Started adding locale translations :)

* Added some more translations

* Working on translating even more pages

* More translations

* Added test default locale retrieval

* replace `intl.formatMessage` with custom `t` hook

* add more translations

* improve title syntax

* add more translations

* translate admin config page

* translated error messages

* add language selecter

* minor fixes

* improve language handling

* add upcoming languages

* add `crowdin.yml`

* run formatter

---------

Co-authored-by: Steve Tautonico <stautonico@gmail.com>

frontend/.eslintrc.json

@@ -1,5 +1,10 @@
 {
-  "extends": ["eslint-config-next", "eslint:recommended", "prettier"],
+  "extends": [
+    "next/babel",
+    "eslint-config-next",
+    "eslint:recommended",
+    "prettier"
+  ],
   "plugins": ["react"],
   "rules": {
     "quotes": ["warn", "double", { "allowTemplateLiterals": true }],