Feat: Support for Microsoft Oauth in Email Channel (#6227)

- Adds the backend APIs required for Microsoft Email Channels

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>
Co-authored-by: Sojan <sojan@pepalo.com>

app/models/channel/email.rb

@@ -12,6 +12,8 @@
 #  imap_login                :string           default("")
 #  imap_password             :string           default("")
 #  imap_port                 :integer          default(0)
+#  provider                  :string
+#  provider_config           :jsonb
 #  smtp_address              :string           default("")
 #  smtp_authentication       :string           default("login")
 #  smtp_domain               :string           default("")
@@ -41,7 +43,7 @@ class Channel::Email < ApplicationRecord
   self.table_name = 'channel_email'
   EDITABLE_ATTRS = [:email, :imap_enabled, :imap_login, :imap_password, :imap_address, :imap_port, :imap_enable_ssl, :imap_inbox_synced_at,
                     :smtp_enabled, :smtp_login, :smtp_password, :smtp_address, :smtp_port, :smtp_domain, :smtp_enable_starttls_auto,
-                    :smtp_enable_ssl_tls, :smtp_openssl_verify_mode, :smtp_authentication].freeze
+                    :smtp_enable_ssl_tls, :smtp_openssl_verify_mode, :smtp_authentication, :provider].freeze
 
   validates :email, uniqueness: true
   validates :forward_to_email, uniqueness: true
@@ -52,6 +54,10 @@ class Channel::Email < ApplicationRecord
     'Email'
   end
 
+  def microsoft?
+    provider == 'microsoft'
+  end
+
   private
 
   def ensure_forward_to_email