feat(ir_camera_system): ir led & eye triggering on face camera strobe

[fouge]

clock ir led and eye camera triggers on rgb/ir strobe (falling edge) to prevent ir light bleed into rgb frame. compute end of next strobe at the end of a face cam strobe pulse with 50us margin. delete face camera triggering on diamond orb: rgb/ir cam is started by pulsing the trigger pin once with new isp firmware.

do not apply settings if rgb/ir face cam is running but wait for new setting to be applied on rgb/ir face camera strobe isr so that timers aren't reset in a middle of a pulse. only reload ir leds settings if wavelength changes.

cameras can still be enabled independently: eye camera can be enabled without face camera strobe signal.

refactor with clearer function names: ir_leds_{enable_pulse, set_pulse_length}, camera_set_exposure_length

still keep same source files for both Diamond & Pearl

• [ ] can we enable rgb streaming without FSIN?
• [ ] ensure focus/mirror sweeps work the same