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

app/models/security/synth_combobox_option.rb

@@ -0,0 +1,20 @@
+class Security::SynthComboboxOption
+  include ActiveModel::Model
+  include Providable
+
+  attr_accessor :symbol, :name, :logo_url, :exchange_acronym, :exchange_mic
+
+  class << self
+    def find_in_synth(query)
+      security_prices_provider.search_securities(query:, dataset: "limited", country_code: Current.family.country).securities.map { |attrs| new(**attrs) }
+    end
+  end
+
+  def id
+    "#{symbol}|#{exchange_mic}" # submitted by combobox as value
+  end
+
+  def to_combobox_display
+    "#{symbol} - #{name} (#{exchange_acronym})" # shown in combobox input when selected
+  end
+end