rpm: enable and start service on first install
See merge request xen-project/xen-guest-agent!78
## 0.5.0 - unreleased
+ ### new features
+
+ * the RPM now enables and starts the service on first install
+ * the RPM now causes xe-guest-utilities to be uninstalled
+ automatically
+
### bugfixes
+* AlmaLinux and Rocky Linux guests are now reported as such, when
+ build against os_info 3.8 or better
* the RPM now replaces xe-guest-utilities-latest too, not only
xe-guest-utilities