Package Source Mapping UI - Add Package Source Mapping in the NuGet Options UI

[nkolev92]

This issue captures all the additions for Package Source Mapping in the NuGet Options UI.

Note that this does not include the package manager UI, that's a different task.

This issue captures creating clarity and ensuring the spec is up to date with whatever gets implemented.

Refer to the design here: https://github.com/NuGet/Home/blob/dev/implemented/2021/PackageSourceMapping.md

As of right now, the design doc seems pretty complete.

Some potential questions.

• How do you onboard to source mapping using the UX (ex. enabling the feature).

cc @JonDouglas

Design primarily captured in #11377

• Package Source Mapping UI - List Package Source Mappings in the NuGet Options UI #11362
• Package Source Mapping UI - Allow the Creation/Removal of package source mappings in the NuGet Options UI #11363
• Package Source Mapping UI - Allow a source to be pinned as default (ie. set *) in the NuGet Options -> Package Sources view. #11364
• https://github.com/NuGet/Client.Engineering/issues/1834
• https://github.com/NuGet/Client.Engineering/issues/1691
• https://github.com/NuGet/docs.microsoft.com-nuget/issues/2799
• https://github.com/NuGet/Client.Engineering/issues/2034
• VS Options - Package Source Mapping should ordered after Package Sources #12271
• [DCR]: Adding a new Package Source in VS Options should be immediately available for a Package Source Mapping #12155
• [Bug Bash] The “source” column of the “Add New Package Source Mapping” dialog doesn’t have the minimum width set which makes it can be dragged out of sight #13355

[nkolev92]

Closing this as complete.