chore: Provider APIs for SMS Channel - Bandwidth (#3889)

fixes: #3888

db/migrate/20220129024443_add_sms_channel.rb

@@ -0,0 +1,11 @@
+class AddSmsChannel < ActiveRecord::Migration[6.1]
+  def change
+    create_table :channel_sms do |t|
+      t.integer :account_id, null: false
+      t.string :phone_number, null: false, index: { unique: true }
+      t.string :provider, default: 'default'
+      t.jsonb :provider_config, default: {}
+      t.timestamps
+    end
+  end
+end