fix: add user argument to paginator.edit

[NeloBlivion]

Summary

Fixes #2381
Paginator.edit sets self.user to the message author... but since you can only edit your own messages, user is set to the bot and so breaks author_check. This changes it so you can specify any user for paginator.edit, otherwise uses the existing user if it was already set.

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.
• I have updated the changelog to include these changes.

[Dorukyum]

As this adds a new parameter, we could have a changelog entry under the "Added" section too.

[Revnoplex]

This should fix #1877 too? As the now dead pr #2105 talked about fixing the exact same missing feature/bug related to both #1877 and #2381

[Lulalaby]

Please stop asking around, if it fixes that, we'll link it on merge