This change allows the user to configure both IMAP and SMTP for an email inbox. IMAP enables the user to see emails in Chatwoot. And user can use SMTP to reply to an email conversation.
Users can use the default settings to send and receive emails for email inboxes if both IMAP and SMTP are disabled.
Fixes#2520
Configuring an agent email also as a support email inbox leads to conversations getting created in a loop if notifications were also configured to the same email.
* feat: added support mailbox to handle email channel (#140)
Added a new mailbox called 'SupportMailbox' to handle all the
incoming emails other than reply emails.
An email channel will have a support email and forward email
associated with it. So we filter for the right email inbox based on
the support email of that inbox and route this to this mailbox.
This mailbox finds the account, inbox, contact (create a new one
if it does not exist) and creates a conversation and adds the
email content as the first message in the conversation.
Other minor things handled in this commit:
* renamed the procs for routing emails in application mailbox
* renamed ConversationMailbox to ReplyMailbox
* Added a fallback content in MailPresenter
* Added a record saving (bang) versions of enabling and disabling
features in Featurable module
* added new factory for the email channel
refs: #140
