Simplify managing investment votes

If I'm right, the `investment_votes` instance variable only exists to
avoid several database queries to get whether the current user has
supported each of the investments.

However, that doesn't make much sense when only one investment is shown.
In this case, the number of queries stays the same, and so we can
simplify the code by rendering the component with an optional parameter.

app/components/budgets/investments/votes_component.rb

@@ -3,7 +3,7 @@ class Budgets::Investments::VotesComponent < ApplicationComponent
   delegate :namespace, :current_user, :voted_for?, :image_absolute_url,
     :link_to_verify_account, :link_to_signin, :link_to_signup, to: :helpers
 
-  def initialize(investment, investment_votes:)
+  def initialize(investment, investment_votes: nil)
     @investment = investment
     @investment_votes = investment_votes
   end
@@ -28,7 +28,11 @@ class Budgets::Investments::VotesComponent < ApplicationComponent
     end
 
     def user_voted_for?
-      @user_voted_for ||= voted_for?(investment_votes, investment)
+      @user_voted_for ||= if investment_votes
+                            voted_for?(investment_votes, investment)
+                          else
+                            current_user&.voted_for?(investment)
+                          end
     end
 
     def display_support_alert?