### 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 (!tile_set.is_valid()) {
		return TileSet::TerrainsPattern();
	}
	
	RBMap<TileSet::TerrainsPattern, int> terrain_pattern_score;
	RBSet<TileSet::TerrainsPattern> pattern_set = tile_set->get_terrains_pattern_set(p_terrain_set);
	ERR_FAIL_COND_V(pattern_set.is_empty(), TileSet::TerrainsPattern());
	for (TileSet::TerrainsPattern &terrain_pattern : pattern_set) {
		int score = 0;
		
		TerrainConstraint terrain_constraint = TerrainConstraint(this, p_position, terrain_pattern.get_terrain());
		const RBSet<TerrainConstraint>::Element *in_set_constraint_element = p_constraints.find(terrain_constraint);
		if (in_set_constraint_element) {
			if (in_set_constraint_element->get().get_terrain() != terrain_constraint.get_terrain()) {
				score += in_set_constraint_element->get().get_priority();
			}
		} else if (p_current_pattern.get_terrain() != terrain_pattern.get_terrain()) {
			continue; 
		}
		
		bool invalid_pattern = false;
		for (int i = 0; i < TileSet::CELL_NEIGHBOR_MAX; i++) {
			TileSet::CellNeighbor bit = TileSet::CellNeighbor(i);
			if (tile_set->is_valid_terrain_peering_bit(p_terrain_set, bit)) {