Initial pass at Synth-based ticker selection (#1392)

* Initial pass at Synth-based ticker selection

* Update _tickers.turbo_stream.erb

* Functional combobox display

* A few cleanup steps

* Linter

* Prevent long strings

* Another step towards functional combobox

* Deprecated files

* Custom Combobox implementation

* Lint

* Test suite fixes

* Lint

* Make direct use of mic codes

* Update splits

* Update trades_test.rb

test/system/trades_test.rb

@@ -9,6 +9,16 @@ class TradesTest < ApplicationSystemTestCase
     @account = accounts(:investment)
 
     visit_account_trades
+
+    Security::SynthComboboxOption.stubs(:find_in_synth).returns([
+      Security::SynthComboboxOption.new(
+        symbol: "AAPL",
+        name: "Apple Inc.",
+        logo_url: "https://logo.synthfinance.com/ticker/AAPL",
+        exchange_acronym: "NASDAQ",
+        exchange_mic: "XNAS"
+      )
+    ])
   end
 
   test "can create buy transaction" do