Electron: investigate to use `requestSingleInstanceLock()` API

Currently VSCode is implementing it’s own solution for preventing a second instance from starting. Electron provides API to do the same but there are differences: https://github.com/electron/electron/blob/7-1-x/docs/api/app.md#apprequestsingleinstancelock

Things we need:

• pass the process environment over (https://github.com/electron/electron/issues/18434)
• communicate between second and first instance to support code --status [1]

[1] code --status will print information about the active window in the first instance to the console of the second instance and thus requires access to the workspace, including remote scenarios.

[deepak1556]

Adding @bpasero comments about the benefits from using the API:

• Might help mitigate multiple dock icon on macOS
• Performance gain (needs to be measured) if runtime handles the communication channel and exit of the new instance
• Handle connection between elevated and non-elevated instances.

[deepak1556]

Good catch, maybe the API can provide an option to allow this default behavior or abort and surface as error to users.

app.requestSingleInstanceLock{{allowAdminLaunch: <boolean>})