Emulator based integration tests of the SC18IS604 GPIO driver

As noted in Running CI Tests Locally it is a common best practice to running regression test suites locally before submit. This checking the buildability and regression of the SC18IS604 GPIO driver with emulated communication components inside a native simulation:

$ west twister \
       --jobs 4 \
       --verbose \
       --inline-logs \
       --integration \
       --testsuite-root bridle/tests/drivers/gpio \
       --tag sc18is604