User verification through organization's DB

[josanFFiG]

This is a Feature Proposal

🎩 Description

Organizations need to check membership for verification against their own member's DB.
Should be taken into account that DB could be on different formats (eg. .csv .xls .mdb etc.)

📌 Related issues

decidim/decidim#2284
decidim/decidim#2024
DiputacioBarcelona/decidim-diba#7

📋 Additional Data

• Decidim deployment where you found the issue:
• Browser & version:
• Screenshot:
• Error messages:
• URL to reproduce the error:

[andreslucena]

There's also File Authorization Handler module, that's the evolution of Decidim Census from DIBA: https://github.com/MarsBased/decidim-file_authorization_handler