libtracker-common: Add a way to test things with old .cfg files
libtracker-common: Add a way to test things with old .cfg files

The TRACKER_USE_CONFIG_FILES envvar now triggers a mode where .cfg
files are dumped into GSettings, but not deleted. The changes done
to GSettings are also dumped to the .cfg file after any
g_settings_apply() call with unapplied data.

hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker