Improve support of primary keys

This splits primary keys across "automatic" primary keys (handled by the database) and manual primary keys (managed by the user). Use the opportunity to improve/clarify the documentation of field metadata attributes.

Test Plan

look at my new tox tests

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Migrated from D3286 (view on Phabricator)

Build is green

Patch application report for D3286 (id=11659)

Rebasing onto 1c93e553...

Current branch diff-target is up to date.

Changes applied before test

commit f520108a8d0abefec3a91967aedbc29fb1a808f8
Author: Nicolas Dandrimont <nicolas@dandrimont.eu>
Date:   Tue Jun 16 10:08:59 2020 +0200

    Improve support of primary keys
    
    This splits primary keys across "automatic" primary keys (handled by the
    database) and manual primary keys (managed by the user). Use the opportunity to
    improve/clarify the documentation of field metadata attributes.

See https://jenkins.softwareheritage.org/job/DSCH/job/tests-on-diff/28/ for more details.

mentioned in merge request !304 (closed)

Merge request was accepted

approved this merge request

Merge request was merged

closed