Remove external utilities from SDK API

[austinabell]

Low confidence suggestion:

near-sdk-js/src/utils.js

Lines 17 to 19 in f03eb1a

	export function encodeCall(contract, method, args) {
	return Buffer.concat([Buffer.from(contract), Buffer.from([0]), Buffer.from(method), Buffer.from([0]), Buffer.from(JSON.stringify(args))])
	}

Probably shouldn't be exposed from the SDK API because it is just a utility used externally from the contract and can't even be used from within because Buffer is not available from the rollup generated code.

This might be a foot gun for developers if they see this within the SDK. Doesn't seem to be used anyway or exported though, so this might just be as simple as removing the code