Add payment method or saved custom fields

For GiveCampus school settings.

The non-recurring template editor offers $PAYMENT_TYPE$; insert it with a clear label and preview the message. It resolves the contribution's display payment type, using the payment subtype when available. Do not hard-code a payment label for every gift.

The custom-fields section renders nonblank saved standard and additional-field values, including supported address/tribute fields, subject to recipient permissions. It does not guarantee that data submitted after payment was present when the initial notification rendered. Missing post-payment answers require checking saved data and send timing; an updated notice is not guaranteed after a post-payment submission. Preview examples are sample data, not proof that a particular gift contains those values.