Default visibility setting of battery monitors in "Battery measurements"

[ReinvdZee]

When clicking the battery drilldown, the user is redirected to a list of battery monitors:

Available battery monitors can be set to 'visible' or 'hidden' in system setup -> Battery monitors:

By default, all battery monitors are hidden, except the active battery monitor. We should improve this by enabling 'dedicated' battery monitors (smartshunts, BMSes, etc.) by default.

The setting to show or hide a battery monitor is e.g. Settings/SystemSetup/Batteries/Configuration/com_victronenergy_battery/2/1/Enabled

[ReinvdZee]

Systemcalc defines several types of battery trackers, each corresponding to a certain service providing battery data. I'd say the com.victronenergy.battery service is the only one dedicated battery monitor. For this type, both a BatteryTracker and a SecondaryBatteryTracker are created. The first is the main battery tracker, and the second tracks /Dc/1/Voltage, e.g. the starter battery voltage.

For example, the smartshunt has both trackers:

We can enable the visibility of the main tracker such that only the main tracker of com.victronenergy.battery services is visible by default (like in the screenshot above). I drafted an implemenation for this.

@izak @mpvader Is this the desired behavior?