[PM-2572] Add new cipher encryption on attachments without key when moving cipher to an org

[LRNcardozoWDF]

Type of change

• [X] Bug fix
• [ ] New feature development
• [ ] Tech debt (refactoring, code cleanup, dependency upgrades, etc)
• [ ] Build/deploy pipeline (DevOps)
• [ ] Other

Objective

When an attachment file gets reencrypted and reuploaded, the new key is ignored by the server. This PR prepares the fix for the mobile side by adding the cipher.key in the attachment's metadata.

Code changes

• Attachment.cs AttachmentView.cs: Added property CipherKey to store the cipher.Key
• src/Core/Models/Domain/Cipher.cs: Added logic to use attachment.CipherKey for decryption if necessary
• src/Core/Services/CipherService.cs: Update the cipher to use cipher.Key and save that value in the attachment object and metadata.

Before you submit

• Please check for formatting errors (dotnet format --verify-no-changes) (required)
• Please add unit tests where it makes sense to do so (encouraged but not required)
• If this change requires a documentation update - notify the documentation team
• If this change has particular deployment requirements - notify the DevOps team