Feat/get latest status extensionmethod

[CelineTrammi]

Add extension methods for Correspondence and Attachment

Description

Previously there was a lot of duplicate code regarding getting the latest status for correspondence and attachment. This was often done using standard filtering on date. However, in the statusRepository classes there are methods of retrieving them there. As each of these calls are asynchronous, another approach is to add extension methods. Extension methods helps with removing a lot of the duplicate code and is arguably easier to read and comprehend compared.

Additions:

• CorrespondenceExtensions.cs
• AttachmentExtensions.cs

I considered creating extensions for the Status objects instead of the whole correspondence and attachment objects, and possibly returning CorrespondenceStatus (as opposed to CorrespondenceStatusEntity). However after looking at the code, retrieving latest status always uses the correspondence/attachment (meaning they are always available), and latest status is typically used with the actual Status, but also the fields StatusChanged and StatusText

Deletions:

• GetLatestStatusByCorrespondenceId
• GetLatestStatusByAttachmentId

As these are not used, they have been temporarily removed. There may come a time where we only want the latest status and no other fields.

Related Issue(s)

• Fiks: hent status fra CorrespondenceStatusRepository istedenfor å hente hele Correspondence og filtrere lokalt #267

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)
• All tests run green

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[Ceredron]

Great use of extension methods!