add task to clear a feature with the specified strategy

This task replicates the "Clear" feature from the dashboard.
With it, a feature can be cleared (unset) using the specified
strategy.

lib/tasks/flipflop.rake

@@ -18,6 +18,12 @@ namespace :flipflop do
     puts "Feature :#{args[:feature]} disabled!"
   end
 
+  desc 'Clears a feature with the specified strategy.'
+  task :clear, %i[feature strategy] => :environment do |_task, args|
+    m.clear_feature! args[:feature], args[:strategy]
+    puts "Feature :#{args[:feature]} cleared!"
+  end
+
   desc 'Shows features table'
   task features: :environment do
     # Build features table...

lib/tasks/support/methods.rb

@@ -41,6 +41,13 @@ def switch_feature!(feature_name, strategy_name, value)
           raise "The :#{strategy_name} strategy doesn't support switching."
         end
       end
+
+      def clear_feature!(feature_name, strategy_name)
+        feature = find_feature_by_name(feature_name)
+        strategy = find_strategy_by_name(strategy_name)
+
+        strategy.clear!(feature.key)
+      end
     end
   end
 end