chant integration: m80 as a declared emulator behind `chant emulator up`

[lex00]

The last M5 item without a home now that the roadmap page is retiring in favor of issues.

chant's EmulatorSpec shape (docker container + HTTP health + endpoint env var) is exactly what m80 already is: one container, /_m80/health, AWS_MICROVM_ENDPOINT. Registering it would make chant emulator up start m80 alongside floci the way it starts floci's aws/azure/gcp today, and behold's serve --local contract would pick it up for free.

kubemicrovm-ops currently starts m80 by hand in scripts/local/local-up.sh; with this landed, that script loses another undeclared edge.