Feature: Installation global config (#839) (#840)

* Renamed concern from Feature to Featurable

* Feature: Installation config (#839)
* Added new model installtion config with corresponding migrations and specs
* Created an installation config yml (key value store model)
* Created a config loader module to load the installaltion configs
* Added this to the config loader seeder
* Changed the account before create hook for default feature enabling to use the feature values from installtion config
* Renamed the feature concern to Featurable to follow the naming pattern for concerns
* Added comments and specs for modules and places that deemed necessary

* Refactored config loader to reduce cognitive complexity (#839)

app/models/concerns/featurable.rb

@@ -0,0 +1,60 @@
+module Featurable
+  extend ActiveSupport::Concern
+
+  QUERY_MODE = {
+    flag_query_mode: :bit_operator
+  }.freeze
+
+  FEATURE_LIST = YAML.safe_load(File.read(Rails.root.join('config/features.yml'))).freeze
+
+  FEATURES = FEATURE_LIST.each_with_object({}) do |feature, result|
+    result[result.keys.size + 1] = "feature_#{feature['name']}".to_sym
+  end
+
+  included do
+    include FlagShihTzu
+    has_flags FEATURES.merge(column: 'feature_flags').merge(QUERY_MODE)
+
+    before_create :enable_default_features
+  end
+
+  def enable_features(names)
+    names.each do |name|
+      send("feature_#{name}=", true)
+    end
+  end
+
+  def disable_features(names)
+    names.each do |name|
+      send("feature_#{name}=", false)
+    end
+  end
+
+  def feature_enabled?(name)
+    send("feature_#{name}?")
+  end
+
+  def all_features
+    FEATURE_LIST.map { |f| f['name'] }.index_with do |feature_name|
+      feature_enabled?(feature_name)
+    end
+  end
+
+  def enabled_features
+    all_features.select { |_feature, enabled| enabled == true }
+  end
+
+  def disabled_features
+    all_features.select { |_feature, enabled| enabled == false }
+  end
+
+  private
+
+  def enable_default_features
+    config = InstallationConfig.find_by(name: 'ACCOUNT_LEVEL_FEATURE_DEFAULTS')
+    return true if config.blank?
+
+    features_to_enabled = config.value.select { |f| f[:enabled] }.map { |f| f[:name] }
+    enable_features(features_to_enabled)
+  end
+end