MFC r346080: Add a smoke test QEMU boot script for CI

MFC r346080: Add a smoke test QEMU boot script for CI

And followon commits:
r346317 (ian): Allow this test script to be run from within src/tools/boot
r346329: Install some entropy for QEMU CI smoke test
r346330: Put QEMU CI smoke test boot log in /tmp if TMPDIR not set
r346748 (bcran): Fix tools/boot/ci-qemu-test.sh and make some improvements
r346961: revert QEMU q35 platform use from r346748
r352063: ci-qemu-test: if firmware is not available, hint at pkg to install
r358472: CI: print wired page count on boot

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