slapos.recipe:wrapper: add py3 support for pidfile and private-tmpfs

These two options were unusable for software releases using python3.

This also adds test coverage for the recipe.
9 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

failed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

passed SlapOS.Eggs.UnitTest-Jerome.Python2

passed SlapOS.Eggs.UnitTest-Jerome.Python3

00:26:08

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.SlapRunner.ResilienceTest-Master

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python2

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python3

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:37:26