Allow toggling of "Background Update" indicator

[CoryFoy]

Is your feature request related to a problem? Please describe.
There are cases where TAK Tracker is being used in the background but it shouldn't be obvious by glancing at the phone that the location is being tracked. Right now when the app is not in the foreground the "Background updating" indicator is on as determined by the time in the upper left corner being highlighted in blue

Describe the solution you'd like
Allow a user to modify an advanced setting to toggle off displaying the indicator.

Additional context
For TAK Tracker we always want this to default to being on and user-modifiable only