Extend interrupt_pin support to MCP23008, MCP23017, MCP23S08, MCP23S17,
and PI4IOE5V6408 GPIO expander components. Same approach as PCF8574/PCA9554:
when configured, the component disables its loop and only wakes on interrupt,
and the cache stays valid between interrupts so binary sensors return from
cache instead of doing I2C/SPI reads every loop iteration.
For MCP23xxx, the interrupt_pin config and C++ logic lives in the shared
MCP23XXXBase template class, so all four variants (I2C 8/16-pin, SPI
8/16-pin) inherit it automatically.
Inspired by jesserockz's work in #11959 which proposed a more comprehensive
interrupt-driven approach with per-pin interrupt status register reading.
This implementation takes a simpler path by leveraging the existing
CachedGpioExpander cache invalidation mechanism.
J. Nick Koston
J. Nick Koston
Keith Burzinski