Enhance OperationMeta to give more info on changes, depending on Operation

Is your feature request related to a problem? Please describe

Operations return an object with a changed attribute that is set to True whenever any changes have been performed on the remote host. It would be very good to have a bit more information available as to what changed, depending on the operation.

Example:

I create users like this:

for user in host.data.users:
    created_user = server.user(
        name=f"Create user {user}",
        user=user,
        groups=('sudo', 'docker'),
        public_keys=[f'files/pub_keys/{user}.authorized_keys'],
        sudo=True,
    )

    if created_user.changed:
        server.shell(
            name=f"Force user {user} on first login to set password",
            commands=[f"passwd -d {user}", f"passwd -e {user}"],
            sudo=True,
        )

The idea is that a newly created user is forced to change their password on first login. What I don't want, however, is having the if-branch executed, just because e.g. an existing user's groups or public_keys changed. But changed is True, no matter what changed, and I would need to look deeper into e.g. changed_user.get_masked_value() to see if a useradd -d … command is present. I didn't get it to work so far, and would like to have functionality like that exposed directly, e.g. by having operations that can give additional info like this return a subclass of OperationMeta with additional attributes.

Start by reading OperationMeta and the get_masked_value behavior, then trace how operation results expose the changed attribute. Define what operation-specific change information must be available for the user example, and consider how completion can be verified without relying on the current masked value inspection.