feat: Support this role in container environments and builds

Feature: Support running this role during container builds and in
container environments.

Reason: This is particularly useful for building bootc derivative OSes.
It's also desirable to run roles in system containers.

Result: These flags enable running the container scenarios in CI, which
ensures that the role works in podman system containers as well as
buildah build environment and thus allows us to officially support this
role for image mode builds.

Actual roles may opt out of this by dropping the corresponding tag.

Author: martinpitt

meta/main.yml

@@ -17,4 +17,10 @@ galaxy_info:
     - el9
     - el10
     - fedora
+    # Support running this role in system container environments, and enable
+    # tests. Remove if not applicable.
+    - container
+    # Support running this role during container builds (mostly useful for
+    # bootc), and enable tests. Remove if not applicable.
+    - containerbuild
 dependencies: []