Add select frame & thread from the context menu

[theIDinside]

This is due to how VSCode operates. "We" (by we, we mean Midas Debug Adapter) will never know what frame or thread is ultimately selected. The problem is described in the issue microsoft/vscode#148004

Therefore, add select commands to the context menu when clicking on individual frames and threads (if possible). I'm pretty sure it's possible to register that.