I have created an extension that provides the default Windows keybindings. It is on the VSCode extension marketplace and called Windows Default Keybindngs.
I have tested it on Linux with VSCode 1.38.0 and 1.36.1.
The new bindings take precedence where there is a conflict, but existing, non-conflicting bindings are still available.
Basically all I did was use HolyBlackCat’s suggestion to run “Preferences: Open Default Keyboard Shortcuts (JSON)” and stuff the result into the appropriate place in package.json. (Plus document it and figure out how to publish it!)
Update 2020-06-05: In response to a question in a comment, I did a search and found LinuxKeybindings, an extension that provides the default Linux bindings. I have not tried it myself but this could be useful for those wanting the Linux bindings instead of Windows bindings.