Add a safety buffer to an estimated gas limit using BigInt.
Write `estimateWithBuffer(estimatedGas, bufferPercent)` where `estimatedGas` is a BigInt and `bufferPercent` a number, returning `estimatedGas` increased by that percentage (integer BigInt math).
Required in your answer: BigInt(
Transpiled, then run in a sandbox
function estimateWithBuffer(estimatedGas, bufferPercent) {
// TODO
}
