Support interrupts

[anecdata]

The breakout has an INT pin, and the chip supports interrupts with thresholds:
https://ams-osram.com/products/sensors/ambient-light-color-spectral-proximity-sensors/ams-tsl25911-ambient-light-sensor

The Adafruit_CircuitPython_TSL2561 has support for interrupts, though it looks like the register API for the TSL2591 differs somewhat.

[yacobucci]

I wanted interrupts for something I was doing and took a stab at it. It's working on my Raspberry Pi 5 for my case. It's easier to work with when the interrupts are off by default, but since that changes current behavior, could be a point of contention.

#30

[anecdata]

In the current release, interrupts enabled but with no way to set up any of the interrupt parameters is practically kind of a NOP, so I doubt the change in behavior should be an issue. Thanks for working on this!