Updated all host mode demos and projects to use the EVENT_USB_Host_DeviceEnumerationC...

Added new USB_Host_ConfigurationNumber global variable to indicate the selected configuration in an attached device.

Renamed global state variables that are specific to a certain USB mode to clearly indicate which mode the variable relates to, by changing the USB_* prefix to USB_Device_* or USB_Host_*.

Removed the HOST_STATE_WaitForDeviceRemoval and HOST_STATE_Suspended host state machine states, as these are no longer required.

Altered the USB_Host_SetDeviceConfiguration() function to update the new USB_Host_ConfigurationNumber global as required.

Moved out the Host mode standard request convenience/helper functions from the architecture specific Host driver files to the architecture agnostic HostStandardReq.c driver file.