Old clients pinned AgentModeIcon to a closed enum and rendered
undefined for unknown values, crashing the route in production
Hermes with no stack trace. Loosen the type to a plain string,
let the client skip rendering when an icon is unregistered, and
add the customModeIcons capability so the daemon downgrades
non-legacy icons to ShieldCheck for clients that pre-date the
open-string contract.
Mohamed Boudra
4911b627f2