installer.sh.in: Fixing DONE variables for set_useraccount and source, Fixing fstype display

[dateiexplorer]

Hello together, found some issues with the DONE variables if the installation process is aborted and resumed afterwards. The following fixes can help to improve the installation process, especially the user creation.

The issue with the various USER_DONE variables is that they are reset if the installation process was aborted and then restarted. The configuration were still there but the user wasn't created because of the DONE variables. Instead of checking the DONE variables now the actual user settings are checked for existence.

Another bug with the SOURCE_DONE is also fixed. Previous the local image was installed instead of the net packages if installation process was aborted and later continued by the user.

A third fix touches the test_network function. Instead of first rm the downloaded file and then execute the xbps-uhelper command the execution order was switched. This ensures that the downloaded file isn't there right after the download process. This fix keeps home direcotries clean.

[dateiexplorer]

I Improved the user creation. If a user is not set up properly a warning is displayed. If you choose to proceed, no user will be created otherwise the installation process will be aborted and you'll be thrown back in the installer menu.

Another "bug" that occur and confusing many people is the fstype of partitions in the menu as described already in issue #130. It shows the fstype of the current installation and not the selected type. So I added a solution that checks if a MOUNTPOINT for the specific device is in the $CONF_FILE. If so, the fstype of the MOUNTPOINT configuration is shown. I think this is more intuitive because you'll get exactly this fstypes if you install the system and this is what you really want to see in the installer.

However, the functionality was tested for the ATA/SCSI/SATA section of the show_partitions function and not for the other. Maybe those need some more improvements?

[Vaelatern]

I guess I'm happy with this. 50% positive, zero % negative.