Add **Web platform with Emscripten**

Source/Tools/Flax.Build/Build/DepsModule.cs

@@ -35,6 +35,7 @@ namespace Flax.Build
             case TargetPlatform.Switch:
             case TargetPlatform.Mac:
             case TargetPlatform.iOS:
+            case TargetPlatform.Web:
                 options.OutputFiles.Add(Path.Combine(path, string.Format("lib{0}.a", name)));
                 break;
             default: throw new InvalidPlatformException(options.Platform.Target);

Source/Tools/Flax.Build/Build/Module.cs

@@ -108,6 +108,7 @@ namespace Flax.Build
             case TargetPlatform.Switch: return "PLATFORM_SWITCH";
             case TargetPlatform.Mac: return "PLATFORM_MAC";
             case TargetPlatform.iOS: return "PLATFORM_IOS";
+            case TargetPlatform.Web: return "PLATFORM_WEB";
             default: throw new InvalidPlatformException(platform);
             }
         }

Source/Tools/Flax.Build/Build/Platform.cs

@@ -170,7 +170,7 @@ namespace Flax.Build
         /// <summary>
         /// Gets the default project format used by the given platform.
         /// </summary>
-        public abstract Projects.ProjectFormat DefaultProjectFormat { get; }
+        public virtual Projects.ProjectFormat DefaultProjectFormat => Projects.ProjectFormat.VisualStudioCode;
 
         /// <summary>
         /// Creates the toolchain for a given architecture.
@@ -343,6 +343,7 @@ namespace Flax.Build
             case TargetPlatform.Switch: return targetArchitecture == TargetArchitecture.ARM64;
             case TargetPlatform.Mac: return targetArchitecture == TargetArchitecture.ARM64 || targetArchitecture == TargetArchitecture.x64;
             case TargetPlatform.iOS: return targetArchitecture == TargetArchitecture.ARM64;
+            case TargetPlatform.Web: return targetArchitecture == TargetArchitecture.x86;
             default: return false;
             }
         }

Source/Tools/Flax.Build/Build/TargetPlatform.cs

@@ -61,6 +61,11 @@ namespace Flax.Build
         /// Running on iPhone.
         /// </summary>
         iOS = 11,
+
+        /// <summary>
+        /// Running on Web.
+        /// </summary>
+        Web = 12,
     }
 
     /// <summary>