brother-brscan4: update to 0.4.11

[shahab-vahedi]

Testing the changes

• I tested the changes in this PR: briefly

Local build testing

• I built this PR locally for my native architecture, x86_64-glibc

Along the way, I have also made the package template look closer
to brother-brscan5. That practically means:

- Adding symlink in /etc/opt/... to configuration files in /opt/...
- Handle udev rule

Also, I have updated the README.voidlinux (URL mentioned in there was
not valid anymore) AND added brscan_{c,g}netconfig files to the
package. Else, "brsaneconfig4" would complain when adding a new device.