Working with old versions of GHC in VSCode

https://github.com/haskell/vscode-haskell/issues/454 is a feature request for better support for working with old versions of haskell-language-server, which is needed for working with older versions of GHC.

This issue is important to me for teaching. For simplicity, I'm using stack for my class this semester and have configured all course projects and autograders to use the same lts. In August, I selected the most recent lts that worked with all of the tools that I wanted to use (hlint, ormolu, vscode) on all platforms. However, in November, haskell-language-server dropped support for GHC-8.10.4 and the auto update meant that vscode stopped working for all of my students. There are workarounds, but I'd like to have a smoother experience.

Following Richard's lead, I'm filing this as an issue in the hope that Haskell Foundation can assist.