Manage failing SSL requests

There are several urls that can not be loaded because of server TLS configurations. For instance:

• https://pax.grsecurity.net/paxctl-0.9.tar.gz: error:1414D172:SSL routines:tls12_check_peer_sigalg:wrong signature type
• https://forge.ocamlcore.org/frs/download.php/1702/ocamlmod-0.0.9.tar.gz: |error:1425F102:SSL routines:ssl_choose_client_version:unsupported protocol`

It would be nice to generate a dedicated exception or log message to list these hosts in sentry. Hosts belonging to this list could then be manually whitelisted in loader download function.

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Migrated from T2334 (view on Phabricator)