[Navigation-Next] Add current nav group to chrome service

[Hailong-am]

Is your feature request related to a problem? Please describe.

when nav group introduced in #7027, when user select a nav group we should store the selected nav group information into chrome service

Describe the solution you'd like

Add a new Observable into chrome_service.ts file

Describe alternatives you've considered

n/a

Additional context

#7027