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/pages/404.tsx

@@ -8,6 +8,7 @@ import {
 } from "@mantine/core";
 import Link from "next/link";
 import Meta from "../components/Meta";
+import { FormattedMessage } from "react-intl";
 
 const useStyles = createStyles((theme) => ({
   root: {
@@ -42,9 +43,11 @@ const ErrorNotFound = () => {
     <>
       <Meta title="Not found" />
       <Container className={classes.root}>
-        <div className={classes.label}>404</div>
+        <div className={classes.label}>
+          <FormattedMessage id="404.title" />
+        </div>
         <Title align="center" order={3}>
-          Oops this page doesn't exist.
+          <FormattedMessage id="404.description" />
         </Title>
         <Text
           color="dimmed"
@@ -53,7 +56,7 @@ const ErrorNotFound = () => {
         ></Text>
         <Group position="center">
           <Button component={Link} href="/" variant="light">
-            Bring me back
+            <FormattedMessage id="404.button.home" />
           </Button>
         </Group>
       </Container>