The documentation for `SEP_DUMP_COMM` was quite unclear and users had to
use the user guide to find out what exactly it did. The new
documentation tries to make the purpose clearer.
This fixes an incorrect check of the device paths during instantiation
of the Septentrio driver that caused the driver to start and not print
an error message.
Having a generic interface over the GPS drivers makes dedicated
functionality for each driver harder. Move the Septentrio driver into
its own module under the `gnss` driver directory, and let it have its
own parameters for only the functionality it requires. This also helps
with adding new features because they only need to be implemented for
the driver that wants it, simplifying testing.