Fix #4931: Add popup voter list for comments.

Show the comment's upvote and downvote count when you hover over a
comment's score. For mods, show the list of voters as well.

app/components/comment_votes_tooltip_component.rb

@@ -0,0 +1,32 @@
+# This component represents the tooltip that displays when you hover over a comment's score.
+class CommentVotesTooltipComponent < ApplicationComponent
+  attr_reader :comment, :current_user
+  delegate :upvote_icon, :downvote_icon, to: :helpers
+
+  def initialize(comment:, current_user:)
+    super
+    @comment = comment
+    @current_user = current_user
+  end
+
+  def votes
+    comment.votes.active.includes(:user).order(id: :desc)
+  end
+
+  def upvote_count
+    votes.select(&:is_positive?).length
+  end
+
+  def downvote_count
+    votes.select(&:is_negative?).length
+  end
+
+  def upvote_ratio
+    return nil if votes.length == 0
+    sprintf("(%.1f%%)", 100.0 * upvote_count / votes.length)
+  end
+
+  def vote_icon(vote)
+    vote.is_positive? ? upvote_icon : downvote_icon
+  end
+end