Added nullable to most Content.Shared files (#3238)

* Add nullable to some Content.Shared files.

* Use [NotNullWhen(true)]

* Undo adding now redundant !'s

* Forgot one

* Add a ton more nullable

* You can guess

* Fix some issues

* It actually compiles now

* Auto stash before merge of "null2" and "origin/master"

* I lied

* enable annotations -> enable

* Revert ActionBlockerSystem.cs to original

* Fix ActionBlockerSystem.cs

* More nullable

* Undo some added exclamation marks

* Fix issues

* Update Content.Shared/Maps/ContentTileDefinition.cs

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

* Resolve some issues

* Remove unused method

* Fix more issues

* Fix more issues

* Fix more issues

* Fix more issues

* Fix issue, rollback SharedGhostComponent.cs

* Update submodule

* Fix issue, invert some if-statements to reduce nesting

* Revert RobustToolbox

* FIx things broken by merge

* Some fixes

- Replaced with string.Empty
- Remove some exclamation marks
- Revert file

* Some fixes

* Trivial #nullable enable

* Fix null ables

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>
Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Shared/Chemistry/DefaultMetabolizable.cs

@@ -1,4 +1,5 @@
-using Content.Shared.Interfaces.Chemistry;
+#nullable enable
+using Content.Shared.Interfaces.Chemistry;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Serialization;
 

Content.Shared/Chemistry/ReagentUnit.cs

@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using System.Globalization;
 using System.Linq;
@@ -204,7 +205,7 @@ namespace Content.Shared.Chemistry
             return reagent < min ? min : reagent > max ? max : reagent;
         }
 
-        public override readonly bool Equals(object obj)
+        public override readonly bool Equals(object? obj)
         {
             return obj is ReagentUnit unit &&
                    _value == unit._value;

Content.Shared/Chemistry/Solution.cs

@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -278,12 +279,13 @@ namespace Content.Shared.Chemistry
 
             Color mixColor = default;
             var runningTotalQuantity = ReagentUnit.New(0);
+            var protoManager = IoCManager.Resolve<IPrototypeManager>();
 
             foreach (var reagent in Contents)
             {
                 runningTotalQuantity += reagent.Quantity;
 
-                if (!IoCManager.Resolve<IPrototypeManager>().TryIndex(reagent.ReagentId, out ReagentPrototype proto))
+                if (!protoManager.TryIndex(reagent.ReagentId, out ReagentPrototype? proto))
                 {
                     continue;
                 }
@@ -322,7 +324,7 @@ namespace Content.Shared.Chemistry
 
             foreach (var (reagentId, quantity) in _contents.ToArray())
             {
-                if (!proto.TryIndex(reagentId, out ReagentPrototype reagent))
+                if (!proto.TryIndex(reagentId, out ReagentPrototype? reagent))
                     continue;
 
                 var removedAmount = reagent.ReactionEntity(entity, method, quantity);

Content.Shared/Chemistry/SolutionContainerCaps.cs

@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using Content.Shared.GameObjects.Components.Chemistry;
 using Robust.Shared.Serialization;