feat: Implement a proper botguard client and potoken minter

[LuanRT]

This adds:

A proper BotGuard client.

It acts as an interface for the BotGuard VM. It can generate responses for user interactions, po tokens, and more.

Example:

/// ...
const botguard = await BG.BotGuardClient.create({
  program,
  globalName,
  globalObj
});

const result = await botguard.snapshot({
  contentBinding: {
    c: "a=6&a2=10&b=SZWDwKVIuixOp7Y4euGTgwckbJA&c=1729143849&d=1&t=7200&c1a=1&c6a=1&c6b=1&hh=HrMb5mRWTyxGJphDr0nW2Oxonh0_wl2BDqWuLHyeKLo",
    e: "ENGAGEMENT_TYPE_VIDEO_LIKE",
    encryptedVideoId: "P-vC09ZJcnM"
  }
});

console.log(result);

WebPo Minter.

Used to create Po Tokens.

Example:

// ...
const webPoSignalOutput: WebPoSignalOutput = [];
const botguardResponse = await botguard.snapshot({ webPoSignalOutput });
 
const payload = [requestKey, botguardResponse];

const integrityTokenResponse = await fetch('https://jnn-pa.googleapis.com/$rpc/google.internal.waa.v1.Waa/GenerateIT', {
  method: 'POST',
  headers: {
    'content-type': 'application/json+protobuf',
    'x-goog-api-key': GOOG_API_KEY,
    'x-user-agent': 'grpc-web-javascript/0.1'
  },
  body: JSON.stringify(payload)
});

const integrityTokenJson = await integrityTokenResponse.json() as [string, number, number, string];

const [integrityToken, estimatedTtlSecs, mintRefreshThreshold, websafeFallbackToken] = integrityTokenJson;

const integrityTokenData = {
  integrityToken,
  estimatedTtlSecs,
  mintRefreshThreshold,
  websafeFallbackToken
};

const webPoMinter = await BG.WebPoMinter.create(integrityTokenData, webPoSignalOutput);

const poToken = await webPoMinter.mintAsWebsafeString(identifier);
console.log(poToken);