feat: allow disabling autodefer through auto_defer methods

[AstreaTSS]

About

This pull request allows "disabling" auto-defers in a command or extension through the helper functions/decorators.

Say, if you had a bot-wide auto-defer (a very common setup), but you wanted one command to specifically not defer (for various reasons). Before, it would take this rather awkward code to achieve the trick:

@slash_command(...)
async def cmd(...):
    ...

cmd.auto_defer = AutoDefer(enabled=False)

With this PR, it's made cleaner:

@slash_command(...)
@auto_defer(enabled=False)
async def cmd(...):
    ...

A similar concept applies with extensions.

Checklist

• The pre-commit code linter has been run over all edited files to ensure the code is linted.
• I've ensured the change(s) work on 3.8.6 and higher.
• I have added the versionadded, versionchanged and deprecated to any new or changed user-facing function I committed.

Pull-Request specification

I've made this pull request: (check all that apply)

• For the documentation
• To add a new feature
• As a general enhancement
• As a refactor of the library/the library's code
• To fix an existing bug
• To resolve #ISSUENUMBER

This is:

• A breaking change