support more information for CAN bus (#6)

* busload, bus state, circle time, bitrate support

* remove setting bitrate - because of PRIVILEGE

* also add bus load and circle time for windows

* support CAN bus bitrate configuration

* also support bitrate configuration for Windows

support device selection page (#5)

* support select pcan devices on windows

* support select CAN device

* still have a warning on windows

* support polling to query CAN devices

* use tokio with async function to improve performance

* need to exit when the application close

* commonise windows and linux