ci-license-scan: Manually check whitelisted files

Files whitelisted in debian/apertis/copyright.whitelist are used to
instruct the scanner process not to raise an error which allows the
pipeline to succeed and merge the change. However, as a side effect, the
entries in debian/apertis/copyright with offending licenses are being
removed, dropping important information.

BOM generator for Apertis binary packages needs the whole information.
scan-copyright scanner must be called without a whitelist, so the
pipeline keeps license information for all the present files in the
source package.

This MR adapts ci-license-scan script to generate license information
for all the files, without failing on whitelisted offending ones.

Link: https://phabricator.apertis.org/T7878



Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>