Favorite Documents extension lets you create links to frequently used code files and then quickly open them as a group or individually in Visual Studio 2010+.
v2.1 now saves and restores the cursor position in a favorite document and adds the ability to create one level of subfolders.
https://tabsstudio.com/
Making Visual Studio perfect 
Any chance of updating to support VS2019?. It would be much appreciated.
I’ve added support for VS 2019 in v2.4.0: https://visualstudioextensions.vlasovstudio.com/2019/02/06/favorite-documents-v2-4-0-adds-support-for-visual-studio-2019/