feat: Clean up email configuration for from and reply to emails (#12453)

We first added conversation continuity for the live chat widget, and
then carried the same logic over to email channels.

The problem was that this added a reply+conversationUUID@domain.com as
the reply-to for emails, which was unnecessary. For email channels, the
reply-to can just be the channel’s own email address.

That extra layer made things more complex than it needed to be. In this
PR, I’ve cleaned up the config so it’s simpler. The table below shows
how it’ll work going forward.

---

| Type | From Email | Reply To Email |
| -- | -- | -- |
| Standard IMAP, SMTP email channel | channel.email | channel.email |
| Google OAuth Email channel | channel.email | channel.email |
| Microsoft OAuth Email channel | channel.email | channel.email |
| Email forwarded to Chatwoot, brought their own SMTP | channel.email |
channel.email |
| Imap to fetch email, Use Chatwoot's SMTP | channel.email if verified
with Chatwoot's SMTP provider. Otherwise account support email |
channel.email |
| Email forwarded to Chatwoot, Use Chatwoot's SMTP | channel.email if
verified with Chatwoot's SMTP provider. Otherwise account support email
| channel.email |
| -- | --  | -- |
| Website Live Chat - Conversation Continuity Inbound Emails enabled|
Account Support Email | reply+{conversation-uuid}@{account_domain} |
| Website Live Chat - Conversation Continuity Inbound Emails disabled|
Account Support Email | Account Support Email |

Fixes https://github.com/chatwoot/chatwoot/issues/10614
Fixes https://github.com/chatwoot/chatwoot/issues/10521
Fixes https://github.com/chatwoot/chatwoot/issues/10300
Fixes https://github.com/chatwoot/chatwoot/issues/10091
Fixes https://github.com/chatwoot/chatwoot/issues/4890
Fixes https://github.com/chatwoot/chatwoot/issues/10676
Fixes https://github.com/chatwoot/chatwoot/issues/10756
Fixes https://github.com/chatwoot/chatwoot/issues/11515
Fixes https://github.com/chatwoot/chatwoot/issues/9471

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

config/features.yml

@@ -214,3 +214,9 @@
   enabled: false
   premium: true
   chatwoot_internal: true
+- name: reply_mailer_migration
+  # This feature is temporary only to migrate reply mailer to new email builder
+  # Once the migration is done, this feature can be removed
+  display_name: Reply Mailer Migration
+  enabled: false
+  chatwoot_internal: true