PersonCard: get top_identifiers from term instead

This is now directly available from the LegislativePeriod object (called
'term') so there's no need to pass it to the initializer.

lib/page/term_table.rb

@@ -60,7 +60,6 @@ def people
         PersonCard.new(
           person:          person,
           term:            term,
-          top_identifiers: top_identifiers
         )
       end
     end

lib/person_cards.rb

@@ -1,12 +1,9 @@
 # frozen_string_literal: true
 
 class PersonCard
-
-  # TODO: pass fewer arguments!
-  def initialize(person:, term:, top_identifiers:)
+  def initialize(person:, term:)
     @person          = person
     @term            = term
-    @top_identifiers = top_identifiers # get from Legislature
   end
 
   def proxy_image
@@ -48,7 +45,11 @@ def memberships
 
   private
 
-  attr_reader :person, :term, :top_identifiers
+  attr_reader :person, :term
+
+  def top_identifiers
+    term.top_identifiers
+  end
 
   def legislature
     term.legislature