Support resume gateway url

[gamer0mega]

Which package is the feature request for?

discord.js

Feature

Approximately a month ago, Discord introduced resume gateway url inside of the ready event, but it looks like discord.js does not have it (NOT the separate ws package)
I have browsed through the code and it appears that WebSocketShard always uses the gateway property of its manager which is wss://gateway.discord.gg/, even when it has to resume, but the ws package has it.

Ideal solution or implementation

Store the resume gateway url inside of the WebSocketShard, and when it's the time to reconnect and resume, use it instead of WebSocketShardManager#gateway which comes from the /gateway/bot endpoint.

Alternative solutions or implementations

No response

Other context

No response