DEV: enable frozen string literal on all files

This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.

Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/actions.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   module Actions
     TIMEOUT_DURATION = 900 # 15 mins

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/advanced_user_narrative.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class AdvancedUserNarrative < Base
     I18N_KEY = "discourse_narrative_bot.advanced_user_narrative".freeze

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/base.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class Base
     include Actions

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/certificate_generator.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class CertificateGenerator
     def initialize(user, date)

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/dice.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class Dice
     MAXIMUM_NUM_OF_DICE = 20

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/magic_8_ball.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class Magic8Ball
     def self.generate_answer

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/new_user_narrative.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'distributed_mutex'
 
 module DiscourseNarrativeBot

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/quote_generator.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'excon'
 
 module DiscourseNarrativeBot

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/track_selector.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class TrackSelector
     include Actions

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/welcome_post_type_site_setting.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseNarrativeBot
   class WelcomePostTypeSiteSetting
     def self.valid_value?(val)