[FEATURE REQUEST] Support for dotnet workloads

[Khaos66]

Please confirm these before moving forward.

• I have searched for my feature proposal and have not found a work-in-progress/duplicate/resolved/discarded issue.
• This proposal is a completely new feature. If you want to suggest an improvement or an enhancement, please use this template.

Describe the new feature

Add the abillity to update dotnet workload

The dotnet sdk has optional workloads that need to be updated, too.

dotnet workload list lists these workloads and the current version.
dotnet workload update updates ALL workloads

Not sure if it's possible to update a single workload. Propably not. So maybe dotnet workloads needs to be a single entry in the Updates view.

Describe how this new feature could help users

The dotnet team releases SDK workload updates that fix problems and add new features from time to time.
The workloads are not updated any other way but via dotnet workload update.
So if the user never cares to update, they will stay out-dated and cause hard to track problems.