Auto-suggest name for new Passkeys

- Use plain client data json everywhere
- Expose AAGUID and backed_up on Credentials
- Make attestation verifiers configurable
- Auto-suggest names for passkeys and show icons

app/models/identity/credential/authenticator.rb

@@ -0,0 +1,12 @@
+class Identity::Credential::Authenticator < Data.define(:name, :icon)
+  REGISTRY = Rails.application.config_for(:passkey_aaguids).each_with_object({}) do |(_key, attrs), hash|
+    authenticator = new(name: attrs[:name], icon: attrs[:icon])
+    attrs[:aaguids].each { |aaguid| hash[aaguid] = authenticator }
+  end.freeze
+
+  class << self
+    def find_by_aaguid(aaguid)
+      REGISTRY[aaguid]
+    end
+  end
+end