Add include_pagination_headers matcher to check Link header in api specs (#29596)

spec/support/matchers/api_pagination.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+RSpec::Matchers.define :include_pagination_headers do |links|
+  match do |response|
+    links.map do |key, value|
+      response.headers['Link'].find_link(['rel', key.to_s]).href == value
+    end.all?
+  end
+
+  failure_message do |header|
+    "expected that #{header} would have the same values as #{links}."
+  end
+end