Draft: Save scan data in a json file and use it as a cached provenance provider if possible

Jenkins job DTSCN/gitlab-builds #278 succeeded in 43 sec.
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added 3 commits

• 02e257e0...4a4daf80 - 2 commits from branch swh/devel:master
• 796fe5e3 - Save scan data in a json file and use it as a cached provenance provider if possible

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Jenkins job DTSCN/gitlab-builds #281 succeeded in 54 sec.
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