Better error message on IOException

[hhyyrylainen]

For example here: https://community.revolutionarygamesstudio.com/t/0-6-0-0-will-not-download/5791
the launcher should have explicit advice that if the error is about access being denied to make sure the launcher has access to the path (potentially deleting it if it iexists already in case some admin locked files are there), or switching to a different Thrive install folder.