spa-pod: add support for custom Id properties

Allows creating and parsing Pod Objects with custom properties.
6 jobs for spa-pod-custom-property in 1 minute and 8 seconds (queued for 8 seconds)
Status Name Job ID Coverage
  Container
passed container_fedora #13867483

00:00:17

passed container_ubuntu #13867484

00:00:17

 
  Build
passed build_on_fedora_no_docs #13867486

00:00:46

passed build_on_fedora_with_docs #13867485

00:00:50

passed build_on_ubuntu_no_gir #13867488

00:00:46

passed build_on_ubuntu_with_gir #13867487

00:00:46