update runner to set date

AdventOfCode/Runner/AOCRunner.cs

@@ -37,6 +37,24 @@ public class AOCRunner
 		}
 	}
 
+	public AOCRunner WithDay(int day)
+	{
+		var problem = _loadedProblems[_selectedYear].FirstOrDefault(d => d.info.Day == day);
+		if (problem == default)
+			throw new ArgumentException($"The no problems have been loaded for the day '{day}' of year '{_selectedYear}'", nameof(day));
+
+		_selectedDay = _loadedProblems[_selectedYear].IndexOf(problem);
+		return this;
+	}
+
+	public AOCRunner WithYear(int year)
+	{
+		if (!_loadedProblems.ContainsKey(year))
+			throw new ArgumentException($"The no problems have been loaded for the year '{year}'", nameof(year));
+		_selectedYear = year;
+		return this;
+	}
+
 	private void InitSizing()
 	{
 		_maxProblemCount = Console.WindowHeight - 9;