Remove the cffi version of poopt

I originally wrote this one in order to support pypy3, but nobody cares
about maintaining it and cpython users regularly use it instead of the C
extension, not knowing it is much slower on this Python interpreter.
8 jobs for bye-pypy in 6 minutes and 36 seconds (queued for 1 second)
Status Job ID Name Coverage
  Lint
failed #33471
mypy

00:03:16

failed #33469
pylint-latest

00:05:53

passed #33470
pylint-plugins

00:06:30

passed #33468
security-check

00:04:16

 
  Test
skipped #33475
pytest-3.10
skipped #33472
pytest-3.7
skipped #33473
pytest-3.8
skipped #33474
pytest-3.9
 
Name Stage Failure
failed
mypy Lint
$ mypy --ignore-missing-imports ./poezio
poezio/windows/inputs.py:12: error: Module "poezio" has no attribute "poopt"
poezio/windows/muc.py:12: error: Module "poezio" has no attribute "poopt"
poezio/ui/types.py:9: error: Module "poezio" has no attribute "poopt"
poezio/ui/render.py:18: error: Module "poezio" has no attribute "poopt"
poezio/tabs/basetabs.py:38: error: Module "poezio" has no attribute "poopt"
Found 5 errors in 5 files (checked 78 source files)
Cleaning up file based variables
ERROR: Job failed: exit code 1
failed
pylint-latest Lint
poezio/windows/inputs.py:12:0: E0611: No name 'poopt' in module 'poezio' (no-name-in-module)
************* Module poezio.core.core
poezio/core/core.py:569:26: E1101: Instance of 'object' has no 'split' member (no-member)
************* Module poezio.ui.render
poezio/ui/render.py:18:0: E0611: No name 'poopt' in module 'poezio' (no-name-in-module)
************* Module poezio.ui.types
poezio/ui/types.py:9:0: E0611: No name 'poopt' in module 'poezio' (no-name-in-module)
Cleaning up file based variables
ERROR: Job failed: exit code 1