Add injectors + injected reagent metabolism via BloodstreamCompo… (#730)

* Add BloodstreamComponent and BloodstreamSystem

New component for metabolizing reagents that other organs like the stomach pass their input reagents to.

* Change StomachComponent to put ingested reagents in bloodstream after delay

Now StomachComponent does not metabolize any reagents. Instead, it tracks how long each reagent has been inside it, and once they pass "digestionDelay" they'll be put inside the bloodstream, where the bloodstream will handle metabolism of the reagent.

* Add reagent injectors

Injects reagents straight into the bloodstream when used on mobs with bloodstreams. Also allows draw/inject from beakers. Does not support drawing blood/reagents from the bloodstream yet.

* Address code review

Make use of `Loc` static class instead of using `ILocalizationManager`. Localize InjectorToggleMode enum properly.

Content.Shared/GameObjects/ContentNetIDs.cs

@@ -40,5 +40,6 @@
         public const uint STACK = 1035;
         public const uint HANDHELD_LIGHT = 1036;
         public const uint PAPER = 1037;
+        public const uint REAGENT_INJECTOR = 1038;
     }
 }