Change setup of stratisd for tests
Change setup of stratisd for tests

Allow stratisd executable to be specified by an environment variable.

Remove support for C executable.

Leave abstract base class; it might be reasonable to extend it with
a non-simulator execution in a near-future version.

Signed-off-by: mulhern <7b51bcf507bcd7afb72bf8663752c0ddbeb517f6@redhat.com>

stratis-storage/stratis-cli,stratis-storage/stratis-cli