devtools

453332ad - Tidy some code in the integration testing. Namely: (#8996)

Tidy some code in the integration testing. Namely: (#8996) * Convert the FlutterDaemonConstants from an enum into a namespaced set of constant strings. In all cases, each enum value was only used to access the 'key' string, so this simplifies to that reality. Also they weren't used as an enumeration. * Reduce the number of JSON map lookups. This makes the code more concise. * Use the `.option`, `.multiOption`, and `.flag` APIs from package:args, avoiding dynamic casting.