Add more robust notification service config

Enables canvas to connect to local service queue by allowing other AWS
SQS keys to be passed into main config.

Test Plan:
  * Start notification service
  * Start canvas jobs with notification failures configured for local
    * copy `config/notification_failures.yml.example` to
      `config/notification_failures.yml`
    * modify `notification_failures.yml` to include sqs_endpoint info
```
development:
  notification_failure_queue_name: notification-service-failures
  use_ssl: false
  sqs_endpoint: sqs.docker
  sqs_port: 9494
  access_key_id: access key id
  secret_access_key: secret access key
```
  * Start canvas with notification service configured for local
    * copy `config/notification_service.yml.example` to
      `config/notification_service.yml`
    * modify `notification_service.yml` to include sqs_endpoint info
```
development:
  notification_service_queue_name: notification-service
  use_ssl: false
  sqs_endpoint: sqs.docker
  sqs_port: 9494
  access_key_id: access key id
  secret_access_key: secret access key
```
  * Enable notification service in rails console
    * `User.find(1).account.root_account.enable_feature!(:notification_service)`
  * Add bad email communication channel to a canvas user
    * Settings -> Add email address 'baduserwithoutdomain@example.com'
    * Confirm communication channel `CommunicationChannel.last.confirm!`
    * Modify email address to remove domain
      * `CommunicationChannel.last.update_attribute(:path, 'baduserwithoutdomain')`
  * Change default email address to bogus one
    * Settings -> email addresses -> click star next to "baduser..."
  * Send message with different account to account with "baduser" email
  * Confirm that message is set to "transmission_error" state from
    notifications admin tools
  * Additionally, "transmission_errors" field can be checked on message
    record in rails console to see actual error message

closes CNVS-27199

Change-Id: I5a6b00f86544dba15598dd1f692524253af42be2
Reviewed-on: https://gerrit.instructure.com/71971
Reviewed-by: Steven Burnett <sburnett@instructure.com>
Tested-by: Jenkins
QA-Review: Gentry Beckmann <gbeckmann@instructure.com>
Product-Review: Jonathan Featherstone <jfeatherstone@instructure.com>

app/models/notification_service.rb

@@ -19,6 +19,9 @@
 require 'aws-sdk'
 
 class NotificationService
+  DEFAULT_CONFIG = {
+    notification_service_queue_name: 'notification-service'
+  }.freeze
 
   def self.process(global_id, body, type, to, remote)
     self.notification_queue.send_message({
@@ -32,11 +35,8 @@ class NotificationService
 
   def self.notification_queue
     return @notification_queue if defined?(@notification_queue)
-    @config ||= ConfigFile.load('notification_service').try(:symbolize_keys)
-    sqs = AWS::SQS.new(
-      access_key_id: @config[:access_key_id],
-      secret_access_key: @config[:secret_access_key],
-      region: @config[:region])
-    @notification_queue = sqs.queues.named(@config[:notification_service_name])
+    @config ||= DEFAULT_CONFIG.merge(ConfigFile.load('notification_service').try(:symbolize_keys))
+    sqs = AWS::SQS.new(@config)
+    @notification_queue = sqs.queues.named(@config[:notification_service_queue_name])
   end
 end

config/notification_failures.yml.example

@@ -1,7 +1,7 @@
 development:
   access_key_id: access_key
   secret_access_key: secret_key
-  # notification_failure_queue_name: notification_service_failures
+  # notification_failure_queue_name: notification-service-failures
   # idle_timeout: 10
   # You can also specify the following values to be passed into the sqs queue's
-  # poll command: initial_timeout, wait_time_seconds, visibility_timeout
+  # poll command: initial_timeout, wait_time_seconds, visibility_timeout

config/notification_service.yml.example

@@ -0,0 +1,4 @@
+development:
+  access_key_id: access_key
+  secret_access_key: secret_key
+  # notification_service_queue_name: notification-service