Lazy migration on host boot — seed app.boxel.realm-servers from legacy realms#5319

lukemelia wants to merge 6 commits into

cs-11655-add-realm-servers-event-typecardstack/boxel:cs-11655-add-realm-servers-event-typefrom

cs-11659-lazy-migration-on-host-boot-derive-trusted-servers-fromcardstack/boxel:cs-11659-lazy-migration-on-host-boot-derive-trusted-servers-fromCopy head branch name to clipboard