### 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
if (cell.source_id != TileSet::INVALID_SOURCE) {
				Ref<TileSetSource> source = tile_set->get_source(cell.source_id);
				Ref<TileSetAtlasSource> atlas_source = source;
				if (atlas_source.is_valid()) {
					tile_data = atlas_source->get_tile_data(cell.get_atlas_coords(), cell.alternative_tile);
				}
			}
			if (tile_data && tile_data->get_terrain_set() == p_terrain_set && tile_data->get_terrain() == p_terrain) {
				connect = true;
			}
		}
		if (connect) {
			cells_with_terrain_center_bit.insert(coords);
		}
	}
	RBSet<TerrainConstraint> constraints;
	
	for (Vector2i coords : p_coords_array) {
		
		TerrainConstraint c = TerrainConstraint(this, coords, p_terrain);
		c.set_priority(10);
		constraints.insert(c);
		
		for (int j = 0; j < TileSet::CELL_NEIGHBOR_MAX; j++) {
			TileSet::CellNeighbor bit = TileSet::CellNeighbor(j);
			if (tile_set->is_valid_terrain_peering_bit(p_terrain_set, bit)) {
				c = TerrainConstraint(this, coords, bit, p_terrain);
				c.set_priority(10);
				if ((int(bit) % 2) == 0) {