[feature] add ts package for express middleware around transaction handling

[ngundotra]

It would be awesome if I could do

import { solanaPayMiddleware } from @solana-pay/middleware

async function createBuyTx(...): Transaction {
}

// under the hood this should do 
// on GET: return the Record on the right
// on POST: tx.serialize({ requireAllSignatures: false }).toString("base64")
export default solanaPayMiddleware(createBuyNFT, {
  label: "my label",
  icon: "https://solanapay.com/src/img/branding/Solanapay.com/downloads/gradient.svg",
});

cc @govarun

[DracocardZ]

import { solanaPayMiddleware } from @solana-pay/middleware

async function createBuyTx(...): Transaction {
}

// under the hood this should do
// on GET: return the Record on the right
// on POST: tx.serialize({ requireAllSignatures: false }).toString("base64")
export default solanaPayMiddleware(createBuyNFT, {
label: "my label",
icon: "https://solanapay.com/src/img/branding/Solanapay.com/downloads/gradient.svg",
});print("draco")