[Siri] Call someone who is not in a direct room

If we ask Siri to call someone we know in some group rooms but we do not have a direct room with him, Siri only answers that "Riot.im does not find xxx."

No files, tests, or entry points are named. Reproduce the Siri request on iOS with a known group-room contact who lacks a direct room, then trace the contact lookup and call flow; done means Siri can initiate the call instead of reporting that the person is not found.

Written by the indexing model from the issue text.