### 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
Vector2i neighbor = get_neighbor_cell(coords, bit);
					if (cells_with_terrain_center_bit.has(neighbor)) {
						constraints.insert(c);
					}
				} else {
					
					HashMap<Vector2i, TileSet::CellNeighbor> overlapping_terrain_bits = c.get_overlapping_coords_and_peering_bits();
					bool valid = true;
					for (KeyValue<Vector2i, TileSet::CellNeighbor> kv : overlapping_terrain_bits) {
						if (!cells_with_terrain_center_bit.has(kv.key)) {
							valid = false;
							break;
						}
					}
					if (valid) {
						constraints.insert(c);
					}
				}
			}
		}
	}
	
	for (TerrainConstraint c : _get_terrain_constraints_from_painted_cells_list(p_layer, painted_set, p_terrain_set, p_ignore_empty_terrains)) {
		constraints.insert(c);
	}
	
	output = terrain_fill_constraints(p_layer, can_modify_list, p_terrain_set, constraints);
	return output;
}
HashMap<Vector2i, TileSet::TerrainsPattern> TileMap::terrain_fill_path(int p_layer, const Vector<Vector2i> &p_path, int p_terrain_set, int p_terrain, bool p_ignore_empty_terrains) {