Enhance security information retrieval and handling (#1826)

* Enhance security information retrieval and handling

- Add support for operating MIC codes in security info fetching
- Update security uniqueness validation to handle unknown securities
- Improve security creation and update logic in Plaid investment sync
- Update combobox and view components to handle operating MIC codes
- Add unknown flag for securities with incomplete information

* Update schema.rb

* Refactor the need for mic codes

* Don't fetch prices unless a security has the necessary mic code

* Deduplication

* Lint

* Update Securities and Plaid Investment Sync

- Modify PlaidInvestmentSync to return plaid_security for USD cash
- Add non-null constraint to Securities ticker column
- Update Securities fixture to use exchange_operating_mic instead of exchange_mic

---------

Signed-off-by: Josh Pigford <josh@joshpigford.com>

app/models/security/synth_combobox_option.rb

@@ -1,13 +1,14 @@
 class Security::SynthComboboxOption
   include ActiveModel::Model
 
-  attr_accessor :symbol, :name, :logo_url, :exchange_acronym, :exchange_mic, :exchange_country_code
+  attr_accessor :symbol, :name, :logo_url, :exchange_acronym, :exchange_country_code, :exchange_operating_mic
 
   def id
-    "#{symbol}|#{exchange_mic}|#{exchange_acronym}|#{exchange_country_code}" # submitted by combobox as value
+    "#{symbol}|#{exchange_operating_mic}" # submitted by combobox as value
   end
 
   def to_combobox_display
-    "#{symbol} - #{name} (#{exchange_acronym})" # shown in combobox input when selected
+    display_code = exchange_acronym.presence || exchange_operating_mic
+    "#{symbol} - #{name} (#{display_code})" # shown in combobox input when selected
   end
 end