[FR] [import-sbom] Import 'copyrightText' field from SPDX file

[bvdm-cpp]

Is your feature request related to a problem? Please describe.
When importing an already cleared/completely filled in SPDX file that also contains the identified copyrightText at the moment this information gets lost, if the package is unknown to Mend the information now needs to be manually filled in afterwards in the WebUI after the import.

Describe the solution you'd like
Take over the content of the 'copyrightText' field when present in the spdx file, after the import it may be marked as 'overwritten' to make clear the information is not from the Mend database but provided by the user (as if the information was manually enterred in the WebUI)