feat: simplify local substrate process management

[harrysolovay]

One can point to a Substrate project or exe.

const process = await substrateProcess({
  path: "./node-template",
  dev: true,
});

They can then reference the process in a beacon.

const chain = C.chain(new C.ProxyBeacon(process.url));

This makes interacting with a local (likely a development) chain a breeze.

This is abstracted over by the test utils. One can do as follows.

import * as C from "../mod.ts";

// Init the local test chain
const node = await C.test.node();

// Reference it
const chain = C.test.chain(node);

// Grab Alice's public key
const alice = await chain.address.alice.asPublicKeyBytes();

// Read her balance
const result = await chain
  .pallet("System")
  .entry("Account", alice)
  .read();

console.log({ result });

// Terminate the local chain when you're done
node.close();