Mark some more relationships as optional

I noticed this was stopping changing your default list visibility bc contact neopets connection can't be empty, so I fixed that!

And then I just decided to scroll through every `belongs_to` relationship and add optional to the ones that jumped out at me lol

app/models/donation.rb

@@ -2,7 +2,7 @@ class Donation < ApplicationRecord
   FEATURE_COST = 500  # in cents = $5.00
 
   belongs_to :campaign
-  belongs_to :user
+  belongs_to :user, optional: true
   has_many :features, class_name: 'DonationFeature'
 
   def to_param

app/models/donation_feature.rb

@@ -1,6 +1,6 @@
 class DonationFeature < ApplicationRecord
   belongs_to :donation
-  belongs_to :outfit
+  belongs_to :outfit, optional: true
 
   validates :outfit, presence: true, if: :outfit_id_present?
 

app/models/user.rb

@@ -18,7 +18,7 @@ class User < ApplicationRecord
   has_many :wanted_items, -> { where(ClosetHanger.arel_table[:owned].eq(false)) },
     through: :closet_hangers, source: :item
 
-  belongs_to :contact_neopets_connection, class_name: 'NeopetsConnection'
+  belongs_to :contact_neopets_connection, class_name: 'NeopetsConnection', optional: true
 
   scope :top_contributors, -> { order('points DESC').where('points > 0') }