tools: invoke all tools in the super-module directory when gopls & modules are used

[hyangah]

As part of the effort to support multi-module workspace (golang/go#32394), vscode-go should run all the tools (go run, go test, dlv, ...) in the super-module directory, instead of the package or the workspace root folder.

• go commands

• adjust wd for debug adapter commands
  ...
  TODO: list all tools

• test how it affects users who direnv or directory-based environment setup

cc @stamblerre @findleyr @heschik @suzmue