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/modules/auth/states/currentWorkspaceState.ts

@@ -20,6 +20,7 @@ export type CurrentWorkspace = Pick<
   | 'isPasswordAuthEnabled'
   | 'hasValidEnterpriseKey'
   | 'subdomain'
+  | 'hostname'
   | 'metadataVersion'
 >;