FIX: prevent re-flagging when we have reviewed flags before (#10010)

FIX: prevent re-flagging when we have reviewed flags before

Fixes an edge case where a review can be reflagged when:
User flags as inappropriate.
Moderator rejects the flag.
Another user re-flags the post as spam.

Before, anyone was able to re-flag as inappropriate despite it being flagged
previously. With this, users are unable to re-flag for the same reason
regardless of reviewable status.

spec/components/post_action_creator_spec.rb

@@ -151,6 +151,26 @@ describe PostActionCreator do
           expect(result.success?).to eq(false)
         end
 
+        it "succeeds with other flag action types" do
+          freeze_time 10.seconds.from_now
+          spam_result = PostActionCreator.create(user, post, :spam)
+
+          expect(reviewable.reload.pending?).to eq(true)
+        end
+
+        it "fails when other flag action types are open" do
+          freeze_time 10.seconds.from_now
+          spam_result = PostActionCreator.create(user, post, :spam)
+
+          inappropriate_result = PostActionCreator.create(Fabricate(:user), post, :inappropriate)
+
+          reviewable.reload
+
+          expect(inappropriate_result.success?).to eq(false)
+          expect(reviewable.pending?).to eq(true)
+          expect(reviewable.reviewable_scores.select(&:pending?).count).to eq(1)
+        end
+
         it "succesfully flags the post if it was reviewed more than 24 hours ago" do
           reviewable.update!(updated_at: 25.hours.ago)
           post.last_version_at = 30.hours.ago