[FEATURE] add support for clamav

[plexmaniax]

For secruity reasons it would be nice to have the aibility to scan upload in forms.

Therefor https://www.clamav.net/ is a good free tool to use.

Could you please add the support?

Regards
Maik

[solverat]

Adding an upload policy validator is now possible directly within your project:
https://github.com/dachcom-digital/pimcore-formbuilder/blob/master/docs/80_FileUpload.md#upload-policy-validator

ClamAV is just one possible server-side tool. We don’t want to present it as the only or required way to handle this. The choice of tools should remain flexible.