Add `.iwyu_ignore` file

This file contains a list of files (shell globbing) that will be ignored by the
IWYU wrapper script, since we have a number of such files in Kaleidoscope that
either can't be parsed properly (because we're using clang and the virtual
hardware device) or will be mangled (either because of IWYU bugs or
peculiarities in the Kaleidoscope code).

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

.iwyu_ignore

@@ -0,0 +1,12 @@
+src/Kaleidoscope.h
+src/Kaleidoscope-LEDControl.h
+src/kaleidoscope/HIDTables.h
+src/kaleidoscope/driver/bootloader/gd32/Base.h
+src/kaleidoscope/driver/led/Base.h
+src/kaleidoscope/driver/led/WS2812.h
+src/kaleidoscope/driver/led/ws2812/config.h
+src/kaleidoscope/driver/mcu/GD32.h
+src/kaleidoscope/driver/storage/GD32Flash.h
+plugins/Kaleidoscope-FirmwareDump/**
+plugins/Kaleidoscope-HostOS/src/kaleidoscope/plugin/HostOS.h
+plugins/Kaleidoscope-Hardware-EZ-ErgoDox/src/kaleidoscope/device/ez/ErgoDox/i2cmaster.h