Add methods to manipulate message attachments (#83)

• Add methods

• Rename to KeepOrModifyAttachments

• Make public

• Exp-Keep

• Fix?

• work?

• Test

• Try fix

• Here we go again

• BULLSHIT

• yep bullshit

• Remove debug statements

• Add KeepAttachments & ModifyAttachments to WebhookBuilder

• Allow to keep attachments on interaction modify & followup modify

• keep attachments defaults now to null

You have to explicit say if you want to remove attachments.
If you add files, you explicit have to say that you want to keep old ones.

• forgor this :P

• [ci skip] Fix format

• Rename TimeOut to Timeout on functions

• Add Slash 11 & audit log timeout

• Add InteractionContext Attachment Parsing

• Fix auditlog object for guild timeouts

• Update DiscordApiClient.cs

Co-Authored-By: Ch. König <[email protected]>

Co-authored-by: Ch. König <[email protected]>