Add overlapping signal bit tests.

[jverkoey]

This is to protect against accidental pollution of the signalsets due to merging commands from multiple vehicles together.

[github-actions]

Coverage Report

📊 Total coverage: 63%

Name                                   Stmts   Miss  Cover
----------------------------------------------------------
python/__init__.py                         0      0   100%
python/can/__init__.py                     0      0   100%
python/can/can_frame.py                  167     11    93%
python/can/command_registry.py           250    133    47%
python/can/repo_utils.py                  21     17    19%
python/can/signals.py                    264     35    87%
python/can/test_can_frame.py             151      1    99%
python/can/test_signals.py                28      0   100%
python/dump_connectables.py              125    125     0%
python/json_formatter.py                 347     67    81%
python/run_tests.py                       34     34     0%
python/signals_testing.py                233    168    28%
python/signalsets/__init__.py              0      0   100%
python/signalsets/loader.py               59     49    17%
python/signalsets/test_year_range.py      62      1    98%
python/signalsets/year_range.py           29      0   100%
python/test_command_registry.py           74      1    99%
python/test_f150.py                       16      3    81%
python/test_json_formatter.py            123      1    99%
python/test_overlappingsignals.py         32      0   100%
python/test_service01.py                  20      3    85%
python/yaml_test_updater.py              148    148     0%
----------------------------------------------------------
TOTAL                                   2183    797    63%