prerequisite dependencies with version constraints

[jaypipes]

gdt test scenarios should have the ability to specify binary/application dependencies that are prerequisites for the test scenario to be executed. These prerequisites should be checked at runtime and return a runtime error if not present. An optional version constraint can be specified that, when present, can be used to determine if an installed version of the dependency complies with the constraint.

name: example-scenario-with-dependencies

depends:
 - kubectl
 - cmctl >= 1.2.3

tests:
 - name: cmctl-check-api
   exec: cmctl check api
 - name: random-kubectl
   exec: kubectl logs -A