Staking and Savings enpoints implementation

[lordtyuk]

As these endpoints are also available it would be nice to have them implemented in the package.

Details:

https://binance-docs.github.io/apidocs/spot/en/#staking-endpoints https://binance-docs.github.io/apidocs/spot/en/#savings-endpoints

[alailsonribeiro]

const Binance = require("binance-api-node").default;
const client = Binance({});
client.privateRequest("GET", "/sapi/v1/staking/position", { product: "STAKING" })