* AlarmController: Add saving alarm time to file
Save the set alarm time to the SPI NOR flash, so it does not reset to
the default value when the watch resets, e.g. due to watchdog timeout
or reflashing of a new version of InfiniTime.
Just like the `Settings.h` `LoadSettingsFromFile()` the previous alarm
at boot (if available) and `SaveSettingsToFile()` the current alarm when
the `Alarm.h` screen is closed (only if the settings have changed).
The alarm-settings file is stored in `.system/alarm.dat`. The `.system`
folder is created if it doesn't yet exist.
Fixes: https://github.com/InfiniTimeOrg/InfiniTime/issues/1330
* alarmController: close .system dir after usage
Close the `lfs_dir` object for the `.system` dir after usage. Otherwise
on the second changed alarm the system will lockup because the `.system`
dir is already open and was never closed.
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Co-authored-by: Galdor Takacs <g@ldor.de>
a0cd439efc