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/graphql/queries/checkUserExists.ts

@@ -10,6 +10,7 @@ export const CHECK_USER_EXISTS = gql`
           id
           displayName
           subdomain
+          hostname
           logo
           sso {
             type

packages/twenty-front/src/modules/auth/graphql/queries/getPublicWorkspaceDataBySubdomain.ts

@@ -7,6 +7,7 @@ export const GET_PUBLIC_WORKSPACE_DATA_BY_SUBDOMAIN = gql`
       logo
       displayName
       subdomain
+      hostname
       authProviders {
         sso {
           id