### 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)

switch (p_what) {
		case NOTIFICATION_READY: {
			if (!Engine::get_singleton()->is_editor_hint() && animation_set.has(autoplay)) {
				set_active(true);
				play(autoplay);
				_check_immediately_after_start();
			}
		} break;
	}
}
void AnimationPlayer::_process_playback_data(PlaybackData &cd, double p_delta, float p_blend, bool p_seeked, bool p_started, bool p_is_current) {
	double speed = speed_scale * cd.speed_scale;
	bool backwards = signbit(speed); 
	double delta = p_started ? 0 : p_delta * speed;
	double next_pos = cd.pos + delta;
	real_t len = cd.from->animation->get_length();
	Animation::LoopedFlag looped_flag = Animation::LOOPED_FLAG_NONE;
	switch (cd.from->animation->get_loop_mode()) {
		case Animation::LOOP_NONE: {
			if (next_pos < 0) {
				next_pos = 0;
			} else if (next_pos > len) {
				next_pos = len;
			}