[Feature] Guide user to turn off battery optimisation

[KolyaKorruptis]

As explained in #82 I frequently missed out on walking data, because MotionMate was turned off by battery optimisation. I'm pretty sure I have seen other apps explain this problem to the user and even open the relevant settings page to turn optimisation off. In the interest of preventing missed data this would be a useful on-boarding feature for MotionMate.

[0xf4b1]

hm, I never had a problem like that on the devices I'm using but I'm aware of such battery optimization features. I'm not sure if this feature behaves equally across devices and always needs to be turned off so that the app can run in the background. I haven't personally seen apps requesting that (but could be because of my phone settings of course). Needs more research how to determine in which cases it is really needed.

[KolyaKorruptis]

To clarify: It happened when the phone was restarted. MotionMate was not automatically loaded on start then. Since I have set my Galaxy S10+ to auto restart once a week at night this meant that MotionMate was effectively silently turned off. Since I disabled battery optimisation MotionMate gets loaded again after a phone restart.

[KolyaKorruptis]

Incidentally I just installed Airguard and while it doesn't request turning off battery optimization, it advises you to do so and provides a button that triggers a simple dialogue. Thought this might be interesting to you, especially since the Airguard is also open source.
These screenshots show the initial setup of Airguard and what happens when you tap the button "Ignore battery optimization":

[nvllz]

Probably the easiest way to implement it, in case you'll want to restart development one day: nvllz@2bfe63f