Add OutputHeadV1State.apply()

[heuer]

OutputHeadV1State is missing a method to apply the state on an output state. I guess OutputState has to be implemented as well.

See wlroots 1.6.2 - wlr_output_management_v1.h

/**
 * Apply the head state on the supplied struct wlr_output_state.
 *
 * Compositors can then pass the resulting struct wlr_output_state to
 * wlr_output_commit_state() or wlr_output_test_state().
 *
 * The position needs to be applied manually by the caller.
 */
void wlr_output_head_v1_state_apply(
    const struct wlr_output_head_v1_state *head_state,
    struct wlr_output_state *output_state);

[heuer]

Note: OutputState is implemented in the wlroots-next branch

https://github.com/flacjacket/pywlroots/blob/wlroots-next/wlroots/wlr_types/output.py#L311