lisa.target: Add hooks

FEATURE

Add lisa.target.Target(hooks={'post-connect': ['echo hello', 'echo
world']}, ...) parameter. This allows running custom commands on the
target after connection, which can be useful to do custom setup on some
devices such as disabling SE Linux.

The commands can be added in target_conf.yml as follows:

target-conf:
    hooks:
        post-connect:
            - echo hello
            - echo world