Add Keysight branding where applicable

Because there is now more than one "product name" per device
type, we have a concept of a "generic product name" which
singularly maps onto a device type.

This change comes with a few small breaking changes within
the C++ API:

DeviceType::GetDeviceTypeString has been renamed to
DeviceType::GetGenericProductName to denote that
the returned value is not device specific and
device->getProductName() is preferable.

The member function DeviceType::toString has been renamed
to DeviceType::getGenericProductName for the same reason.

The DeviceType std::ostream& operator<< has been removed
to avoid accidental use of the generic product name.

include/icsneo/icsneoc.h

@@ -337,6 +337,9 @@ extern bool DLLExport icsneo_getProductName(const neodevice_t* device, char* str
  *
  * In the case of a neoVI FIRE 2, this function will write a string "neoVI FIRE 2" with a NULL terminator into str.
  *
+ * Note that icsneo_getProductName should *always* be preferred where available, as the product name may change based on device-specific
+ * factors, such as the serial number.
+ *
  * The constant ICSNEO_DEVICETYPE_LONGEST_NAME is defined for the client application to create static buffers of the correct length.
  *
  * See also icsneo_describeDevice().