zef should use azure for its CI

[ugexe]

zef should switch from using travis/appveyor/circle-ci to azure for CI

• See rakudo's azure-pipelines.yml for reference

• The repo is setup in azure piplines already, so producing a azure-piplines.yml file should be all that is needed

• MoarVM only; no need to setup a JVM variant

[ugexe]

A nearly working example can be found here -- 9bca3a5

All its missing to be merged into master is for when any of the commands in TEST_COMMANDS fails it will fail the build (currently if one of the commands fails it will still show up as a success, unlike the commands prior to those which will fail the build on non-0 exit)