### Godot version

4.2 RC2

### System information

Any

### Issue description

AnimationMixer separates the accuracy of how discrete keys are retrieved when seeking between internal seeking and external seeking. FYI: https://github.com/godotengine/godot/pull/80708.

Since AnimationPlayer currently treats everything as an internal seek, so it needs to propagate the external seek information.

### Steps to reproduce

Seek AnimationTrackEditor

### Minimal reproduction project

[gd_anim_unittest_1.zip](https://github.com/godotengine/godot/files/13492063/gd_anim_unittest_1.zip)

return speed_scale;
}
float AnimationPlayer::get_playing_speed() const {
	if (!playing) {
		return 0;
	}
	return speed_scale * playback.current.speed_scale;
}
void AnimationPlayer::seek(double p_time, bool p_update, bool p_update_only) {
	if (!active) {
		return;
	}
	_check_immediately_after_start();
	playback.current.pos = p_time;
	if (!playback.current.from) {
		if (playback.assigned) {
			ERR_FAIL_COND_MSG(!animation_set.has(playback.assigned), vformat("Animation not found: %s.", playback.assigned));
			playback.current.from = &animation_set[playback.assigned];
		}
		if (!playback.current.from) {
			return; 
		}
	}
	playback.seeked = true;
	if (p_update) {
		_process_animation(0, p_update_only);
		playback.seeked = false; 
	}
}
void AnimationPlayer::advance(double p_time) {