Allow SafetyHardware to run without bumpers or e-stops

[pascalzauberzeug]

Motivation

The hardware safety module hard-required both EStopHardware and BumperHardware instances via assert isinstance(...) in _generate_lizard_code().
This blocked simpler robot variants that legitimately ship without bumpers and/or without e-stops (e.g. small devkit configurations) from using the same SafetyHardware class.

Implementation

_generate_lizard_code() drops the e-stop and bumper isinstance assertions and emits the pin-watching when blocks only when the matching hardware is present and exposes pins.
estop_active and bumper_active are always declared, so the enable/disable transitions stay a single pair of rules regardless of which inputs exist.

Progress

• I chose a meaningful title that completes the sentence: "If applied, this PR will..."
• I chose meaningful labels (if GitHub allows me to so).
• I documented breaking changes and set the 'breaking change' label if needed
• The implementation is complete.
• Tests with a real hardware have been successful (or are not necessary).
• Pytests have been added (or are not necessary).
• Documentation has been added (or is not necessary).