### 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_INDEX_V(p_layer, (int)layers.size(), TileSetSource::INVALID_ATLAS_COORDS);
	
	const HashMap<Vector2i, TileMapCell> &tile_map = layers[p_layer].tile_map;
	HashMap<Vector2i, TileMapCell>::ConstIterator E = tile_map.find(p_coords);
	if (!E) {
		return TileSetSource::INVALID_ATLAS_COORDS;
	}
	if (p_use_proxies && tile_set.is_valid()) {
		Array proxyed = tile_set->map_tile_proxy(E->value.source_id, E->value.get_atlas_coords(), E->value.alternative_tile);
		return proxyed[1];
	}
	return E->value.get_atlas_coords();
}
int TileMap::get_cell_alternative_tile(int p_layer, const Vector2i &p_coords, bool p_use_proxies) const {
	ERR_FAIL_INDEX_V(p_layer, (int)layers.size(), TileSetSource::INVALID_TILE_ALTERNATIVE);
	
	const HashMap<Vector2i, TileMapCell> &tile_map = layers[p_layer].tile_map;
	HashMap<Vector2i, TileMapCell>::ConstIterator E = tile_map.find(p_coords);
	if (!E) {
		return TileSetSource::INVALID_TILE_ALTERNATIVE;
	}
	if (p_use_proxies && tile_set.is_valid()) {
		Array proxyed = tile_set->map_tile_proxy(E->value.source_id, E->value.get_atlas_coords(), E->value.alternative_tile);
		return proxyed[2];
	}
	return E->value.alternative_tile;
}
TileData *TileMap::get_cell_tile_data(int p_layer, const Vector2i &p_coords, bool p_use_proxies) const {