feat(custom-domains): allow to register a custom domain (without UI) (#9879)

# In this PR
- Allow to register a custom domain
- Refacto subdomain generation

# In other PRs
- Add UI to deal with a custom domain
- Add logic to work with custom domain

packages/twenty-front/src/pages/settings/workspace/SettingsHostnameEffect.tsx

@@ -0,0 +1,28 @@
+import { isDefined } from '~/utils/isDefined';
+import { useEffect } from 'react';
+import { currentWorkspaceState } from '@/auth/states/currentWorkspaceState';
+import { useRecoilValue } from 'recoil';
+import { useGetHostnameDetailsQuery } from '~/generated/graphql';
+
+export const SettingsHostnameEffect = () => {
+  const { refetch } = useGetHostnameDetailsQuery();
+
+  const currentWorkspace = useRecoilValue(currentWorkspaceState);
+
+  useEffect(() => {
+    let pollIntervalFn: null | ReturnType<typeof setInterval> = null;
+    if (isDefined(currentWorkspace?.hostname)) {
+      pollIntervalFn = setInterval(async () => {
+        refetch();
+      }, 3000);
+    }
+
+    return () => {
+      if (isDefined(pollIntervalFn)) {
+        clearInterval(pollIntervalFn);
+      }
+    };
+  }, [currentWorkspace?.hostname, refetch]);
+
+  return <></>;
+};