Add JSON RSpec formatter for e2e tests

Exposes `status_issue`, `quarantine`, and `screenshot` metadata in test
results in a JSON format, as well as all the other data we currently get
from the JUnit XML format report.

qa/qa/support/json_formatter.rb

+# frozen_string_literal: true
+
+require 'rspec/core/formatters'
+
+module QA
+  module Support
+    class JsonFormatter < RSpec::Core::Formatters::JsonFormatter
+      RSpec::Core::Formatters.register self, :message, :dump_summary, :stop, :seed, :close
+
+      def dump_profile(profile)
+        # We don't currently use the profile info. This overrides the base
+        # implementation so that it's not included.
+      end
+
+      def stop(notification)
+        # Based on https://github.com/rspec/rspec-core/blob/main/lib/rspec/core/formatters/json_formatter.rb#L35
+        # But modified to include full details of multiple exceptions
+        @output_hash[:examples] = notification.examples.map do |example|
+          format_example(example).tap do |hash|
+            e = example.exception
+            if e
+              exceptions = e.respond_to?(:all_exceptions) ? e.all_exceptions : [e]
+              hash[:exceptions] = exceptions.map do |exception|
+                {
+                  class: exception.class.name,
+                  message: exception.message,
+                  backtrace: exception.backtrace
+                }
+              end
+            end
+          end
+        end
+      end
+
+      private
+
+      def format_example(example)
+        {
+          id: example.id,
+          description: example.description,
+          full_description: example.full_description,
+          status: example.execution_result.status.to_s,
+          file_path: example.metadata[:file_path],
+          line_number: example.metadata[:line_number],
+          run_time: example.execution_result.run_time,
+          pending_message: example.execution_result.pending_message,
+          status_issue: example.metadata[:status_issue],
+          quarantine: example.metadata[:quarantine],
+          screenshot: example.metadata[:screenshot]
+        }
+      end
+    end
+  end
+end