Allow setting IgnoreExtraArgs on an individual basis (#998)

* Allow setting IgnoreExtraArgs on an individual basis

* Remove passing in the flag as a separate parameter

* VS plz

* Push the RunMode setting out to its own attribute, because fox wants consistency.

Bonus: Removes the need for that godawful 'RunMode.Default'.

* Revert previous commit

* Fox doesn't like module-wide switches 😒

src/Discord.Net.Commands/CommandService.cs

@@ -6,7 +6,6 @@ using System.Linq;
 using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.DependencyInjection;
 using Discord.Commands.Builders;
 using Discord.Logging;