Fix flags.n?Bool is incorrectly ignored

[Coxxs]

Bug description:

import { Api } from 'telegram'

// globalPrivacySettings#bea2f424 flags:# archive_and_mute_new_noncontact_peers:flags.0?Bool = GlobalPrivacySettings;

let t1 = new Api.GlobalPrivacySettings({
  archiveAndMuteNewNoncontactPeers: false
})
console.log(t1.getBytes())
// expect: <Buffer 24 f4 a2 be 01 00 00 00 37 97 79 bc>
// actual: <Buffer 24 f4 a2 be 00 00 00 00> ❌

let t2 = new Api.GlobalPrivacySettings({
  flags: 1,
  archiveAndMuteNewNoncontactPeers: false
})
console.log(t2.getBytes())
// expect: <Buffer 24 f4 a2 be 01 00 00 00 37 97 79 bc>
// actual: <Buffer 24 f4 a2 be 00 00 00 00> ❌

let t3 = new Api.GlobalPrivacySettings({

})
console.log(t3.getBytes())
// expect: <Buffer 24 f4 a2 be 00 00 00 00>
// actual: <Buffer 24 f4 a2 be 00 00 00 00> ✔

[painor]

hmm I remember fixing a similar bug a while ago with the same API method. maybe I missed this one.