Bug 1: when generating the default debug configuration
because there is no user-configured one, the extension
dropped noDebug field and caused the program to run with
debugging enabled. Fix it (goDebugConfiguration.ts)

Bug 2: when debug adapter receives noDebug request, it
runs the program with `go run` instead of invoking the
program through dlv. The `go run` will not work in modules
mode if the command runs outside the main module. Set
cwd accordingly.

Fixes microsoft#3121

TESTED=manually with the example attached in microsoft#3121