basic admin endgame view and add (#3)

Reviewed-on: #3

lib/chesstrainer/fen.ex

@@ -0,0 +1,13 @@
+defmodule Chesstrainer.FEN do
+  @spec color_from_fen(String.t()) :: :white | :black | nil
+  def color_from_fen(fen) do
+    fen
+    |> String.split(" ")
+    |> Enum.at(1)
+    |> color_initial_to_color_atom()
+  end
+
+  defp color_initial_to_color_atom("b"), do: :black
+  defp color_initial_to_color_atom("w"), do: :white
+  defp color_initial_to_color_atom(_), do: nil
+end