Add user_guild_settings support

[Ratismal]

In the ready event, discord sends two properties specific to ClientUsers - UserSettings and UserGuildSettings. UserSettings has already been wrapped, so this PR aims to wrap UserGuildSettings.

This is accomplished by create two new structures: ClientUserGuildSettings and ClientUserChannelOverrides. These contain wrappings for the user guild settings, and the former contains a Collection of the latter.

Additionally, the Guild and GuildChannel classes both have new properties obtained from these wraps.

I didn't implement the actions required to modify these settings, and will look into doing that in the future (I didn't implement because I wasn't sure how to do it).

I also didn't know the best way to accomplish this, so feel free to give feedback or suggestions on reimplementation.

Thank you for your time.

[devsnek]

you could replace these waterfalls with try/catch

get muted() {
  if (this.client.user.bot) return null;
  if (!this.client.user.guildSettings) return null;
  if (!this.client.user.guildSettings.get(this.guild.id)) return null;
  if (!this.client.user.guildSettings.get(this.guild.id).channelOverrides) return false;
  if (!this.client.user.guildSettings.get(this.guild.id).channelOverrides.get(this.id)) return false;
  return this.client.user.guildSettings.get(this.guild.id).channelOverrides.get(this.id).muted;
}

to

get messageNotifications() {
  try {
    return this.client.user.guildSettings.get(this.guild.id).channelOverrides.get(this.id).muted;
  } catch (err) {
    return false;
  }
}

[aemino]

This needs a rebase.

[Ratismal]

As requested by @GusCaplan, switched waterfalls to try/catches

Also did some if bot return null checks

[devsnek]

@Ratismal this needs a rebase

[devsnek]

@Ratismal is this ready to merge

[devsnek]

try/catch