SWHRemoteAPI: Enable to set timeout on the sent requests

Currently, no timeout values are set when sending HTTP requests to external SWH servers (for instance swh-indexer).

As the Python requests module does not set any timeout values by default, this can result in code hanging for minutes or more in client applications (for instance in swh-web when requesting filetype, language or license when one wants to display a content).

Being able to set timeout values to use within the SWHRemoteAPI class through configuration would be a nice feature to have.

Related swh-web#1060 (closed)

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Migrated from T1061 (view on Phabricator)