Add /api/v1/accounts/familiar_followers to REST API (#17700)

* Add `/api/v1/accounts/familiar_followers` to REST API

* Change hide network preference to be stored consistently for local and remote accounts

* Add dummy classes to migration

* Apply suggestions from code review

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

spec/presenters/familiar_followers_presenter_spec.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe FamiliarFollowersPresenter do
+  describe '#accounts' do
+    let(:account) { Fabricate(:account) }
+    let(:familiar_follower) { Fabricate(:account) }
+    let(:requested_accounts) { Fabricate.times(2, :account) }
+
+    subject { described_class.new(requested_accounts, account.id) }
+
+    before do
+      familiar_follower.follow!(requested_accounts.first)
+      account.follow!(familiar_follower)
+    end
+
+    it 'returns a result for each requested account' do
+      expect(subject.accounts.map(&:id)).to eq requested_accounts.map(&:id)
+    end
+
+    it 'returns followers you follow' do
+      result = subject.accounts.first
+
+      expect(result).to_not be_nil
+      expect(result.id).to eq requested_accounts.first.id
+      expect(result.accounts).to match_array([familiar_follower])
+    end
+
+    context 'when requested account hides followers' do
+      before do
+        requested_accounts.first.update(hide_collections: true)
+      end
+
+      it 'does not return followers you follow' do
+        result = subject.accounts.first
+
+        expect(result).to_not be_nil
+        expect(result.id).to eq requested_accounts.first.id
+        expect(result.accounts).to be_empty
+      end
+    end
+
+    context 'when familiar follower hides follows' do
+      before do
+        familiar_follower.update(hide_collections: true)
+      end
+
+      it 'does not return followers you follow' do
+        result = subject.accounts.first
+
+        expect(result).to_not be_nil
+        expect(result.id).to eq requested_accounts.first.id
+        expect(result.accounts).to be_empty
+      end
+    end
+  end
+end