Show currently owned artifacts from the choose artifact menu

**Issue by [chaorace](https://github.com/chaorace)**
_Monday Jan 09, 2017 at 08:49 GMT_
_Originally opened as https://github.com/CQUI-Org/cqui/issues/236_

----

Currently there's no way to review your owned artifacts before the game forces you to choose an artifact when using an archaeologist at an antiquity site

[More Info](https://www.reddit.com/r/civ/comments/5mqlkl/long_feedback_on_civ6_from_a_longtime_series_fan/)

Start at the choose artifact menu and trace the archaeologist flow when an antiquity site requires a choice. Identify where the player's owned artifacts are available to the UI, then make them reviewable before selection; done means the menu shows currently owned artifacts before the game forces a choice.

Written by the indexing model from the issue text.