APDS9960 refactor

[soypat]

PTAL @deadprogram @alankrantas @aykevl

Changes:

• Remove heap allocations
• Handle all errors
• Much more idiomatic status and enable config setting/getting
• idiomatic transaction based I2C error handling
• simplify some parts of code.
• Change ~ character in comments (rendered as strikethrough in newer versions of gopls)

Still WIP: needs testing on my side.

[soypat]

So it turns out what I have here is not an APDS9960, but rather an APDS9930 🤦 - guess I won't be able to test.