IAR: Add tests covering IAR toolchains
Run the tests only if enabled explicitly by an undocumented cache entry. We will enable it on hosts known to have the toolchains.
Once accepted, IAR can publish the results to the CMake Dashboard from which Kitware also can make use of. We are initially looking into running Nightly using a Linux machine with the IAR Build Tools installed for the all the supported targets, namely: arm, avr, rh850, riscv, rl78 and rx.
Cc: @jlonnberg @micaelbo
Issue: #23308
Edited by Brad King