fix: correctly import extendable classes

[NotSugden]

Please describe the changes this PR makes and why it should be merged:
fixes #4742
This PR changes the GuildMember and User classes to import Presence (and VoiceState on GuildMember) using Structures.get(...) rather than a require import, to correct instantiate any custom extended class

Notes: the NewsChannel and ClientPresence classes seem to not extend TextChannel and NewsChannel respectively, but i wasn't sure the best way to go about fixing that, so i've left it for now

Status

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

Semantic versioning classification:

• This PR changes the library's interface (methods or parameters added)
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
• This PR only includes non-code changes, like changes to documentation, README, etc.