[adc] Refactor ADS1115 driver

[niklaut]

Solved Problem

Two main problems:

1. ADS1115 would not be recognized after a reboot, only after a power cycle.
2. ADS1115 would spam the console when there were I2C transmission issues due to motor EMI (specifically during takeoff and landing).

The driver code is also a bit too optimistic and doesn't log any comms errors.

Solution

I've refactored the driver to be more robust.

1. The ADS1115 lacks an ID register, so the driver checked the CONFIG register for default values. This only works once after a power cycle, since the driver reconfigures the CONFIG register and then after a reboot the values don't match any more. I'm now instead checking the threshold registers, since the driver does not touch them.
2. Debouncing via counter is done to detect if the device failed to prevent spam when a single I2C transaction failed. In addition the channel list is kept as a bitmask to allow retries of failed channels.

Also added perf counter to track comms errors.

Changelog Entry

For release notes:

Bugfix: Robustify ADS1115 driver communications

Alternatives

Burn the I2C garbage.

Test coverage

Tested in hardware by shorting the I2C pins to induce comms failures. Driver recovers and doesn't spam the console.