Use BluetoothError in _bleio

[tannewt]

This better differentiates errors than using OSError everywhere.

[dhalbert]

This is a very nice cleanup.

One thing to check: do these str/repr/print properly as _bleio.RoleError, etc? These appear to be the first native-module-namespace exceptions we have in the code base.

[tannewt]

Ok @dhalbert please take another look. Printing now includes the module by overriding the print method.

Adafruit CircuitPython 5.0.0-beta.0-19-g5e857fdb6-dirty on 2019-11-21; Adafruit Feather nRF52840 Express with nRF52840
>>> import _bleio
>>> raise _bleio.BluetoothError("test")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
_bleio.BluetoothError: test
>>> e = _bleio.BluetoothError("test")
>>> str(e)
'test'
>>> repr(e)
"_bleio.BluetoothError('test',)"
>>>

[dhalbert]

I may have asked for too much. Here's CPython and current CircuitPython:
testing.py:

class MyException(Exception):
    pass

CPython:

Python 3.6.8 (default, Oct  7 2019, 12:59:55) 
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import testing
>>> raise testing.MyException
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
testing.MyException
>>> str(testing.MyException)
"<class 'testing.MyException'>"
>>> str(testing.MyException())
''
>>> repr(testing.MyException())
'MyException()'
>>> 

CircuitPython 5.0.0-beta.0:

>>> import testing
>>> raise testing.MyException
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
MyException: 
>>> str(testing.MyException(3))
'3'
>>> repr(testing.MyException(3))
'MyException(3,)'
>>> 

[dhalbert]

The print change now matches CPython, but the repr() change does not. Could you undo that? That's the last thing. Thanks!
See
#2311 (comment)

[tannewt]

Easy enough. Please take another look.

Adafruit CircuitPython 5.0.0-beta.0-20-g521c7531b-dirty on 2019-11-21; Adafruit Feather nRF52840 Express with nRF52840
>>> import _bleio
>>> raise _bleio.BluetoothError("test 2")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
_bleio.BluetoothError: test 2
>>> e = _bleio.BluetoothError("test 2")
>>> str(e)
'test 2'
>>> repr(e)
"BluetoothError('test 2',)"

[dhalbert]

Thanks for doing this!