Added new spam_flag to Accounts, replacing is_flagged_as_spam

• Added:
- new spam_flag to Accounts, replacing is_flagged_as_spam
- null/0: no spam, 1: spam, 2: safe from spam

• Updated:
- Comment, Status to reflect changes

• Todo:
- Fully remove is_flagged_as_spam
- Update SortingQueryBuilder

db/migrate/20210218235403_add_spam_flag_to_accounts.rb

@@ -0,0 +1,5 @@
+class AddSpamFlagToAccounts < ActiveRecord::Migration[6.0]
+  def change
+  	add_column :accounts, :spam_flag, :integer, null: true
+  end
+end