docs: undocument private constructors

[SpaceEEC]

Please describe the changes this PR makes and why it should be merged:

This PR removes documentation for private constructors.
Those being documented confused library consumers into thinking that they are supposed / intended to instantiate those classes themselves.

Some constructors were intended to be documented due to Structures.extend use-cases, but this feature has, since then, been removed.

Changed classes:

• Shard
• ShardClientUtil
• BaseGuildTextChannel
• ClientPresence
• DMChannel
• GuildBan
• GuildChannel
• GuildEmoji
• GuildTemplate
• Message
• MessageReaction
• Presence
• Role
• Sticker
• StickerPack
• StoreChannel
• ThreadChannel
• ThreadMember
• Typing
• User
• VoiceState
• Widget
• WidgetMember

This PR also modifies the types to no longer allow instantiation where unintended, this includes few more classes than listed above.

Status and versioning classification:

• 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
• This PR only includes non-code changes, like changes to documentation, README, etc.

[ImRodry]

Was gonna submit the review about the external links as soon as Jiralite did it so LGTM xD

[ImRodry]

Actually, most of these constructors are public in the typings, could you go through them and make them private?

[tremby]

Is there a way, short of @ts-expect-error, I can opt out of this for my tests? I use these constructors to produce fixtures for the purpose of unit testing my application.

[kyranet]

There is one: Reflect.construct().