How adapt extension to Visual Studio 2019?

I found the solution for the problem. It is in catalog.json file inside PowerQuerySdk.vsix file. You should change part of the file from:

"Microsoft.VisualStudio.Component.CoreEditor":"[15.0,16.0)"}

to:

"Microsoft.VisualStudio.Component.CoreEditor":"[15.0,17.0)"}

. I didn't suspect that the mention of CoreEditor may be in this file. But obviously you should change the version of MSBuild to 17, just as you should do in extension.vsixmanifest, as it is described in the post of Mads Kristensen above. Up to now all works fine for me :-).