feat: add Message._raw_data

[tibue99]

Summary

This PR adds Message.data, which is useful for handling message data or creating transcripts.

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.

[JustaSqu1d]

MessagePayload is not a documented class. Please add the class to documentation.

[DA-344]

Or maybe document it as dict on the doc string and type annotate it as MessagePayload

[JustaSqu1d]

Or maybe document it as dict on the doc string and type annotate it as MessagePayload

MessagePayload is not documented and shouldn't be used as a type hint for a public attribute.

[tibue99]

MessagePayload is not documented and shouldn't be used as a type hint for a public attribute.

It's done this way for interaction.data. If I should add MessagePayload to the docs, please tell me where to add it.

[Dorukyum]

Do we really need to store the raw message data publicly? Interaction.data exists mainly because it's documented.

[JustaSqu1d]

Do we really need to store the raw message data publicly? Interaction.data exists mainly because it's documented.

Are you suggesting something like message._data or message.__data?

[Dorukyum]

I'm skeptical about the necessity of this attribute

[tibue99]

This attribute is useful for handling transcripts and other cases where messages need to be stored. It doesn't matter to me if it's public or private, but I strongly recommend adding it. Users should be able to use it freely if they need to.

[Paillat-dev]

I see how having Message.data might be incorrect since data is not an attribute of the discord object. Maybe something like Message.payload or Message._payload or Message.raw_data might make more sense? Idk

[Lulalaby]

rename to raw_data
make private

[Lulalaby]

I can see value to adding it, but only as undocumented private field.