hc_sr04: Improve accuracy by measuring microseconds

[clashlab]

What's new

• The furi_get_tick() function has millisecond granularity. This commit changes it to the CYCCNT counter that achieves microsecond granularity when combined with furi_hal_cortex_instructions_per_microsecond().
• Instead of measuring by 17 cm steps (1ms = 17.2cm), we now have 0.017 cm steps.
• Also improve speed of sound equation to show temperature and humidity variations (now using 20°C/68°F and 50% relative humidity)

Verification

• Plug a HC-SR04 module to the gpio
• Launch the [HC-SR] Dist. Sensor application
• Press OK multiple times while moving away from a surface
• The "Echo:" is given in microseconds (us)
• The "Distance:" increases smoothly

Checklist (For Reviewer)

• PR has description of feature/bug
• Description contains actions to verify feature/bugfix
• I've built this code, uploaded it to the device and verified feature/bugfix

[xMasterX]

Thanks!