Update Lecture-Recording relationship and add Lecture cancellation status

The commit introduces notable changes to the Lecture-Recording model relationship in our application and adds a new cancellation status to Lecture model.

Models Lecture and Recording previously had a belongs_to :recording and belongs_to :lecture relationship respectively. However, this setup was not reflecting the correct relationship between these two entities in the actual educational setup where a lecture can have a recording but a recording is always of a lecture. Thus, the relationship has been revised to has_one :recording in Lecture and belongs_to :lecture in Recording models.

Also, added the ability to mark a lecture as "cancelled". This addresses the requirement of representing real-world scenarios where lectures are sometimes cancelled. This cancellation status is then reflected in the Attendance Tracker view and is also handled in the ScrapePanoptoJob.

Additionally, new changes are reflected in the application's schema, migration files, admin dashboard, and stylesheets (for displaying cancelled lectures).

app/models/lecture.rb

@@ -1,7 +1,7 @@
 class Lecture < ApplicationRecord
   belongs_to :course
   has_one :attendance
-  belongs_to :recording, optional: true
+  has_one :recording
 
   def week_number
     ((start_time.beginning_of_week - course.semester_start_date.to_time) / 1.week).floor + 1

app/models/recording.rb

@@ -1,6 +1,7 @@
 # This is a Foreign Object Reference Table, keyed to the external data source by #recording_uuid
 class Recording < ApplicationRecord
   belongs_to :course
+  belongs_to :lecture, optional: true
 
   def recording_url
     return nil if recording_uuid.nil?
@@ -17,4 +18,12 @@ class Recording < ApplicationRecord
 
     title
   end
+
+  def create_lecture!(fixup_time: false)
+    Lecture.create!(
+      title: nice_title,
+      course: course,
+      recording: self
+    )
+  end
 end