Align naming with UTM's AppleScript "Configuration Suite"

[mobileskyfi]

UTM has extensive AppleScript support. While AppleScript cannot be directly used here (since building UTM packages happens at GitHub), it's naming scheme ideally be similar in manifest and templates.

See "UTM Configuration Suite", https://docs.getutm.app/scripting/reference/

Currently naming is largely based on the config.plist names. But using the terms from AppleScript seems better. Right now if a manifest has to change the Plist directly, it forced to use the CapitalCased property names from XML, so mainly about that it looks lame in pkl.

Whether it should happen in the UTM.pkl classes or in utmzip.pkl, IDK yet. More tracking now.