ingest major gitlab instances

As per comment [1], here is a limited list:

|----------------+----------------------------------------+-------------+----------------+-----------|
| listing status | url                                    | instance    | # listed repos | # origins |
|----------------+----------------------------------------+-------------+----------------+-----------|
| done           | https://gitlab.com/api/v4              | gitlab      |         964329 |    965554 |
| done           | https://salsa.debian.org/api/v4/       | debian      |          23757 |      9782 |
| done           | https://framagit.org/api/v4/           | framagit    |          12134 |     12153 |
| done           | https://gitlab.inria.fr/api/v4/        | inria       |           1606 |      1606 |
| done           | https://gitlab.gnome.org/api/v4/       | gnome       |           3825 |      3904 |
| done           | https://gitlab.freedesktop.org/api/v4/ | freedesktop |           1949 |      2849 |
| done           | https://0xacab.org/api/v4/             | riseup      |            883 |       884 |
| done           | https://gitlab.common-lisp.net/api/v4  | common-lisp |            551 |       731 |
| done           | https://gite.lirmm.fr/api/v4           | gite.lirmm  |            292 |       293 |
|----------------+----------------------------------------+-------------+----------------+-----------|

• [1] https://forge.softwareheritage.org/#1111

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Migrated from T1139 (view on Phabricator)