Modify error handling for timed out signals when connecting.

[rosesyrett]

This commit puts responsibility on anything with a .connect method to raise its own ConnectionTimeoutError, to be then picked up by the DeviceCollector, or not. This simplifies the complex error handling requiring timeouts to be handled at the asyncio level and passed up the called via (now redefined) NotConnected exceptions.

fixes #48

[callumforrester]

Definitely the right idea and I'm onboard, see individual comments and also the following about approach:

The approach in most default devices seems to be:

try:
    some_device_specific_connection()
except TimeoutError:  # or CANothing or similar
    raise ConnectionTimeoutError(some_device_specific_source)

Does this lose us information from the original error? Would we not be better off with something like this?

try:
    some_device_specific_connection()
except TimeoutError as ex:  # or CANothing or similar
    raise ConnectionTimeoutError(some_device_specific_source) from ex

[evalott100]

New plan:

[coretl]

Let's discuss the string formatting offline

Tom reviewed instead