Update for Cynthion analyzer USB API changes

[martinling]

Depends on greatscottgadgets/cynthion#87.

Updates how Packetry searches for and displays available Cynthion devices.

Changes are as follows:

1. Preliminary UI code cleanups.
2. Update available speeds when device selection is changed.
3. Name devices simply as Cynthion, unless duplicated, in which case disambiguate with serial number or bus/address.
4. Display all Cynthion devices found, including ones that cannot be used. For unusable devices, keep track of why.
5. Adjust methods to match Update analyzer descriptors and request handling cynthion#87

One detail I'm not sure of yet is how best to display the reasons for devices not being usable, but that doesn't have to be in this PR.