Add salt steps to make sure that the right files have executable bits

[kushaldas]

While working on the RPM packaging of securedrop-workstation I found that rpmbuild is acting too smart, and removing the executable bit from the files as it wishes. Example:

*** WARNING: ./srv/salt/sd/sd-svs/application-x-sd-xfer.xml is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-svs/open-in-dvm.desktop is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-svs/mimeapps.list is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-svs/README is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-svs/decrypt-sd-submission.desktop is executable but has empty or no shebang, removing executable bit
mangling shebang in /srv/salt/sd/sd-svs/decrypt-sd-submission from /usr/bin/env python3 to #!/usr/bin/python3
*** WARNING: ./srv/salt/sd/sd-svs/dot-profile is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-svs/mimeapps-sd-svs-disp.list is executable but has empty or no shebang, removing executable bit
mangling shebang in /srv/salt/sd/sd-journalist/pipereader.py from /usr/bin/env python3 to #!/usr/bin/python3
*** WARNING: ./srv/salt/sd/sd-journalist/mimeapps.list is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-journalist/do-not-open.desktop is executable but has empty or no shebang, removing executable bit
mangling shebang in /srv/salt/sd/sd-journalist/do-not-open-here from /usr/bin/env python3 to #!/usr/bin/python3
*** WARNING: ./srv/salt/sd/sd-journalist/sd-process-download.desktop is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-journalist/sd-process.Feedback is executable but has empty or no shebang, removing executable bit
*** WARNING: ./srv/salt/sd/sd-journalist/sd-process.Feedback-dom0 is executable but has empty or no shebang, removing executable bit
mangling shebang in /srv/salt/sd/sd-journalist/sd-process-download from /usr/bin/env python3 to #!/usr/bin/python3
*** WARNING: ./srv/salt/sd/sd-journalist/sd-process-display is executable but has empty or no shebang, removing executable bit

We should add steps in Salt to make sure that these files are with right executable bits. Also, there are a few scripts with wrong shabang lines.