Refactor account deletion process and improve invitation functionalities

The account deletion process has been refactored to send account deletion emails from the AccountWebhooksService instead of from the deletePersonalAccount service. This has resulted in the addition of the AccountWebhooksService and modification of the seeds.sql file to trigger a webhook after account deletion. Along with this, the account invitation functionalities within the accountInvitations service have been considerably enhanced, making it much clearer and easier to use.

supabase/seed.sql

@@ -2,6 +2,17 @@
 -- In production, you should manually create webhooks in the Supabase dashboard (or create a migration to do so).
 -- We don't do it because you'll need to manually add your webhook URL and secret key.
 
+-- this webhook will be triggered after deleting an account
+create trigger "accounts_teardown" after delete
+on "public"."accounts" for each row
+execute function "supabase_functions"."http_request"(
+  'http://host.docker.internal:3000/api/db/webhook',
+  'POST',
+  '{"Content-Type":"application/json", "X-Supabase-Event-Signature":"WEBHOOKSECRET"}',
+  '{}',
+  '1000'
+);
+
 -- this webhook will be triggered after every insert on the accounts_memberships table
 create trigger "accounts_memberships_insert" after insert
 on "public"."accounts_memberships" for each row