Gdsfactory

- rename `end_straight` to `end_straight_length`
- rename `start_straight` to `start_straight_length`

- add pad_pitch to `resistance_sheet`
- enable multimode waveguide in straight_heater_meander
- add `grating_coupler_elliptical_arbitrary`
- add `grating_coupler_elliptical_lumerical` using lumerical parametrization
- rename `grating_coupler_elliptical2` to `grating_coupler_circular`. rename `layer_core` to `layer`, `layer_ridge` to `layer_slab` for a more consistent parametrization of other grating couplers.
- add Component.add_padding

- pad has vertical_dc port

- add `gf.functions.move_port_to_zero`
- `gf.routing.add_fiber_single` has new parameter `zero_port` that can move a port to (0, 0)
- add fixme/routing
- enable `gf.read.from_yaml` to read ports that are defined without referencing any reference

- decorate `gf.path.extrude` with cell, to avoid duplicated cell names
- enforce contact_startLayer_endLayer naming convention
- gf.grid accepts rotation for reference
- add pydantic validator class methods to Path and CrossSection
- CrossSection has a `to_dict()`
- rename Component `to_dict` to `to_dict()`: is now a method instead of a property
- rename Component `pprint` to `pprint()`: is now a method instead of a property
- rename Component `pprint_ports` to `pprint_ports()`: is now a method instead of a property
- Component.mirror() returns a container

- decorators that return new component also work in cell