### Godot version

v4.0.beta11.official [91713ced8]

### System information

MX Linux 21

### Issue description

In Godot 3, TileMap had methods get_used_cells() and get_used_cells_by_id(). Godot 4's TileMap only has get_used_cells() and is missing get_used_cells_by_id().

get_used_cells_by_id() is highly useful in multiple cases, for example when trying to get all cells that are of road type, to randomly spawn a car.

Re-implementing get_used_cells_by_id() should be simple. The method could simply call get_used_cells(), and ignore all cells that are of the wrong ID.

### Steps to reproduce

N/A

### Minimal reproduction project

N/A
ERR_FAIL_COND(p_layer_id < -1 || p_layer_id >= (int)layers.size());
	selected_layer = p_layer_id;
	emit_signal(SNAME("changed"));
	
	for (unsigned int layer = 0; layer < layers.size(); layer++) {
		_rendering_update_layer(layer);
	}
}
int TileMap::get_selected_layer() const {
	return selected_layer;
}
void TileMap::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE: {
			_clear_internals();
			_recreate_internals();
		} break;
		case NOTIFICATION_EXIT_TREE: {
			_clear_internals();
		} break;
	}
	
	if (tile_set.is_valid()) {
		_rendering_notification(p_what);
		_physics_notification(p_what);
		_navigation_notification(p_what);
	}
}
Ref<TileSet> TileMap::get_tileset() const {