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/share/showErrorModal.tsx

@@ -2,6 +2,7 @@ import { Button, Stack, Text } from "@mantine/core";
 import { useModals } from "@mantine/modals";
 import { ModalsContextProps } from "@mantine/modals/lib/context";
 import { useRouter } from "next/router";
+import { FormattedMessage } from "react-intl";
 
 const showErrorModal = (
   modals: ModalsContextProps,
@@ -31,7 +32,7 @@ const Body = ({ text }: { text: string }) => {
             router.back();
           }}
         >
-          Go back
+          <FormattedMessage id="common.button.go-back" />
         </Button>
       </Stack>
     </>