[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[build][groups] annotate 'misc' and 'test' modules

This allows us to generate a bootdata.bin which excludes them,
reducing it from 4.52MB to 2.65MB

The default bootdata.bin still includes all modules.

Change-Id: If13bfcacba9386a691e6b7c380eed53d67bb44eb

[usb] Add beginnings of USB peripheral mode support

This change adds three new DDK protocols for USB peripheral support:

- MX_PROTOCOL_USB_DCI
The DCI stands for "device controller interface".
This protocol is implemented by drivers for the actual USB controller hardware.
It is analogous to the MX_PROTOCOL_USB_HCI protocol for the host controller drivers.

- MX_PROTOCOL_USB_DEVICE
This is the protocol for the "usb-device" driver, which is the platform independent
layer to the USB peripheral stack.
This protocol provides ioctls for configuring how the USB peripheral controller
appears to the host. It supports ioctls for setting the USB device, configuration
and string descriptors that the host sees.
The "usb-device" driver creates devmgr devices with protocol MX_PROTOCOL_USB_FUNCTION
for each interface in the configuration descriptor.

- MX_PROTOCOL_USB_FUNCTION
This protocol is what various USB function drivers will bind to.
A USB function driver implements a specific piece of functionality corresponding
to a USB interface. For example, a USB HID function driver would allow the Magenta
device to appear as a HID device to the USB host it is connected to.

This change also adds:

- The "usb-device" driver, which binds to MX_PROTOCOL_USB_DCI and creates child devices
with protocol MX_PROTOCOL_USB_FUNCTION based on the USB configuration descriptor
set via ioctl_usb_device_set_config_desc()

- The "usb-function-test" driver. This driver doesn't do anything yet, but it implements
the MX_PROTOCOL_USB_FUNCTION protocol and will be flushed out to do loop back testing
for USB peripheral mode.

- The "usb-virtual-bus" driver. This driver creates a virtual USB host controller and
device controller and proxies USB transactions between the two sides.
This allows testing of the USB peripheral stack on devices without actual USB peripheral
controller hardware.

- The "usbctl" command line tool. This can be used to enable or disable the USB virtual bus,
simulate device connect and disconnect events on the virtual bus, and also
initialize the USB device driver to use the "usb-function-test" function.

To try this out, run:

usbctl virtual enable
usbctl device init-test
usbctl virtual connect

After that you should see a device corresponding to the usb-function-test function in the lsusb output.

So far only USB control requests have been tested.
There is plumbing in place for transfers on other endpoint types, but this hasn't been tested yet.

Change-Id: I302c37246bb887060c3e7f4baa58da1f825e388b