fix(xxxable): follow more properly with discord behavior

[tignear]

Please describe the changes this PR makes and why it should be merged:
In rare cases, the result returned by the current XXXable property may not return the exact result, but it will return the correct result.
However, it seems difficult to maintain this, so consider removing this property.

• Cannot delete channels that are not viewable/connectable(have CONNECT permission).
• Cannot edit messages on channels that cannot send messages.
  • Cannot edit messages on channels that cannot view messages.
• Cannot pin messages on channels that cannot view messages.
• Cannot delete messages on channels that cannot view messages.
• Messages that are not system messages can be pinned.
  • fix(Message): pinnable returning false in non-DEFAULT messages #6585

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

[tignear]

Which should I use permissionsFor().has(X) or permissionsFor().has(X,false)?
This is work as same(It seems that I was confused when I created f28178c).

[NotSugden]

GuildChannel#permissionsFor can return null if the member for the client user is uncached

Stale

[tignear]

Partial testing is here: https://github.com/tignear/discord.js-pr-6551-test/blob/master/main.test.js