wip: libcoap integration with Zephyr

[mniestroj]

Work in progress libcoap integration with Zephyr:

west update
west patch
west build -b qemu_x86 samples/libcoap

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 7c17a6f):

https://golioth-zephyr-sdk-doxygen-dev--pr334-libcoap-fofw9v9w.web.app

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[sam-golioth]

Closing as stale. We're no longer exploring using libcoap in Zephyr.