New Setting: workbench.settings.openDefaultKeybindings
New Action: workbench.action.openDefaultKeybindingsFile

Currently, {"workbench.settings.openDefaultSettings": false} allows users to disable the side-by-side default/user settings view, instead allowing us to view our customized settings file in isolation when using the workbench.action.openSettings command.

A corresponding option does not yet exist for workbench.action.openGlobalKeybindingsFile, although it would be equally useful.

Additionally, something like @sandy081's workbench.action.openRawDefaultSettings contribution in f8c9ed8 should be implemented to allow access of the default keybindings if workbench.settings.openDefaultKeybindings is disabled.