use word-sized params in scd4x self-calibration

[dankamongmen]

scd4x self-calibration passes bool and bool* to execute_cmd(), but this function eventually swaps its 16-bit argument words. a bool is typically represented by a single byte, and thus the swap() reads and writes past the end of the storage, canonical undefined behavior. instead, copy the bool to a local uint16_t, and pass that as the single word. in the get() variant, copy the uint16_t back to the bool on success.