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/src/i18n/locales.ts

@@ -0,0 +1,51 @@
+import danish from "./translations/da";
+import german from "./translations/de";
+import english from "./translations/en";
+import spanish from "./translations/es";
+import french from "./translations/fr";
+import portugueze from "./translations/pt";
+import thai from "./translations/th";
+import chineseSimplified from "./translations/zh-CN";
+
+export const LOCALES = {
+  ENGLISH: {
+    name: "English",
+    code: "en",
+    messages: english,
+  },
+  GERMAN: {
+    name: "Deutsch",
+    code: "de",
+    messages: german,
+  },
+  FRENCH: {
+    name: "Français",
+    code: "fr",
+    messages: french,
+  },
+  PORTUGUEZE: {
+    name: "Português",
+    code: "pt",
+    messages: portugueze,
+  },
+  DANISH: {
+    name: "Dansk",
+    code: "da",
+    messages: danish,
+  },
+  THAI: {
+    name: "ไทย",
+    code: "th",
+    messages: thai,
+  },
+  SPANISH: {
+    name: "Español",
+    code: "es",
+    messages: spanish,
+  },
+  CHINESE_SIMPLIFIED: {
+    name: "简体中文",
+    code: "zh-CN",
+    messages: chineseSimplified,
+  },
+};