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/components/admin/configuration/TestEmailButton.tsx

@@ -1,6 +1,7 @@
 import { Button, Stack, Text, Textarea } from "@mantine/core";
 import { useModals } from "@mantine/modals";
 import { useState } from "react";
+import { FormattedMessage } from "react-intl";
 import useUser from "../../../hooks/user.hook";
 import configService from "../../../services/config.service";
 import toast from "../../../utils/toast.util";
@@ -65,7 +66,7 @@ const TestEmailButton = ({
         }
       }}
     >
-      Send test email
+      <FormattedMessage id="admin.config.smtp.button.test" />
     </Button>
   );
 };