Automatically send a11y stats

[winsmith]

The Swift SDK should automatically send various information about accessibility settings like font size in its default payload.

[nevillco]

I might be interested in implementing this whenever I get the chance next, because I agree these would be nice signals to have for justifying further a11y development.

I'm curious though, are we okay with auto-opting-in users to these additional payload values? Should we offer some kind of configuration, like:

let configuration = TelemetryManagerConfiguration(appID: "<YOUR-APP-ID>")
configuration.defaultPayload = [
    .iOSPlatform, // existing values such as build number
    .accessibility,
]

[winsmith]

I think they should default to on but with the option to disable maybe?