Feature: Conversation Continuity with Email (#770)

* Added POC for mail inbox reply email
* created mailbox and migratuion for the same
* cleaned up sidekiq queues and added the queues for action mailbox and active storage
* created conversation mailbox and functionlaity to create a message on the conversation when it's replied

* Added UUID to conversation to be used in email replies

* added migration to add uuid for conversation
* changed parsing and resource fetching to reflect matching uuid and
  loading conversation alone
* cleaned up conversation mailbox.rb

* Added content type & attribute for message

* Added the new reply email to outgoing emails
* Added migration to accounts for adding domain and settings
* Modified seeds to reflect this changes
* Added the flag based column on account for boolean settings
* Added the new reply to email in outgoing conversation emails based on conditions

* Added dynamic email routing in application mailbox
* Added dynamic email routing in application mailbox
* Added a catch all deafult empty mailbox
* Added annotation for account

* Added the complete email details & attachments to the message
* Added the complete email details to the message in content_attributes, like subject, to, cc, bcc etc
* Modified the mail extractor to give a serilaized version of email
* Handled storing attachments of email on the message

* Added incoming email settings, env variables

* [#138] Added documentation regarding different email settings and variables

* Fixed the mail attachments blob issue (#138)
* Decoided attachments were strings and had to construct blobs out fo them to work with active storage
* Fixed the content encoding issue with mail body
* Fixed issue with Proc used in apllication mailbox routing
* Fixed couple of typos and silly mistakes

* Set appropriate from email for conversation reply mails (#138)
* From email was taken from a env variable, changed it to take from account settings if enabled
* Set the reply to email correctly based on conversation UUID
* Added commented config ind development.rb for mailbox ingress

* Added account settings for domain and support email (#138)
* Added the new attributes in accounts controller params whitelisting, api responses
* Added options for the the new fields in account settings

* Fixed typos in email continuity docs and warnings

* Added specs for conversation reply mailer changes (#138)
* Added specs for
  * conversation reply mailer
  * Accounts controller
  * Account and Conversation models

* Added tests for email presenter (#138)

* Specs for inbound email routing and mailboxes (#138)

app/presenters/mail_presenter.rb

@@ -0,0 +1,59 @@
+class MailPresenter < SimpleDelegator
+  attr_accessor :mail
+
+  def initialize(mail)
+    super(mail)
+    @mail = mail
+  end
+
+  def subject
+    encode_to_unicode(@mail.subject)
+  end
+
+  def content
+    return @decoded_content if @decoded_content
+
+    @decoded_content = parts.present? ? parts[0].body.decoded : decoded
+    @decoded_content = encode_to_unicode(@decoded_content)
+    @decoded_content
+  end
+
+  def attachments
+    # ref : https://github.com/gorails-screencasts/action-mailbox-action-text/blob/master/app/mailboxes/posts_mailbox.rb
+    mail.attachments.map do |attachment|
+      blob = ActiveStorage::Blob.create_after_upload!(
+        io: StringIO.new(attachment.body.to_s),
+        filename: attachment.filename,
+        content_type: attachment.content_type
+      )
+      { original: attachment, blob: blob }
+    end
+  end
+
+  def number_of_attachments
+    mail.attachments.count
+  end
+
+  def serialized_data
+    {
+      content: content,
+      number_of_attachments: number_of_attachments,
+      subject: subject,
+      date: date,
+      to: to,
+      from: from,
+      in_reply_to: in_reply_to,
+      cc: cc,
+      bcc: bcc,
+      message_id: message_id
+    }
+  end
+
+  private
+
+  # forcing the encoding of the content to UTF-8 so as to be compatible with database and serializers
+  def encode_to_unicode(str)
+    current_encoding = str.encoding.name
+    str.encode(current_encoding, 'UTF-8', invalid: :replace, undef: :replace, replace: '?')
+  end
+end