Security resolver and health checker (#2281)

* Setup health check

* Security health checker cron

* Use resolver throughout codebase

* Use resolver for trade builder

* Add security health checks to schedule

* Handle no provider

* Lint fixes

app/models/security.rb

@@ -9,6 +9,8 @@ class Security < ApplicationRecord
   validates :ticker, presence: true
   validates :ticker, uniqueness: { scope: :exchange_operating_mic, case_sensitive: false }
 
+  scope :online, -> { where(offline: false) }
+
   def current_price
     @current_price ||= find_or_fetch_price
     return nil if @current_price.nil?
@@ -25,10 +27,6 @@ class Security < ApplicationRecord
     )
   end
 
-  def has_prices?
-    exchange_operating_mic.present?
-  end
-
   private
     def upcase_symbols
       self.ticker = ticker.upcase