Add support for one-time PayPal donations

service/src/main/graphql/braintree/ChargePayPalOneTimePayment.graphql

@@ -0,0 +1,9 @@
+# https://graphql.braintreepayments.com/reference/#Mutation--chargePaymentMethod
+mutation ChargePayPalOneTimePayment($input: ChargePaymentMethodInput!) {
+  chargePaymentMethod(input: $input) {
+    transaction {
+      id,
+      status
+    }
+  }
+}

service/src/main/graphql/braintree/CreatePayPalOneTimePayment.graphql

@@ -0,0 +1,7 @@
+# https://graphql.braintreepayments.com/reference/#Mutation--createPayPalOneTimePayment
+mutation CreatePayPalOneTimePayment($input: CreatePayPalOneTimePaymentInput!) {
+  createPayPalOneTimePayment(input: $input) {
+    approvalUrl,
+    paymentId
+  }
+}

service/src/main/graphql/braintree/TokenizePayPalOneTimePayment.graphql

@@ -0,0 +1,8 @@
+# https://graphql.braintreepayments.com/reference/#Mutation--tokenizePayPalOneTimePayment
+mutation TokenizePayPalOneTimePayment($input: TokenizePayPalOneTimePaymentInput!) {
+  tokenizePayPalOneTimePayment(input: $input) {
+    paymentMethod {
+      id
+    }
+  }
+}