Add swiftgen build script for generating image and color assets.

ElementX/SupportingFiles/Assets.xcassets/Colors/Contents.json

@@ -2,5 +2,8 @@
   "info" : {
     "author" : "xcode",
     "version" : 1
+  },
+  "properties" : {
+    "provides-namespace" : true
   }
 }

ElementX/SupportingFiles/Assets.xcassets/Images/Contents.json

@@ -0,0 +1,9 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  },
+  "properties" : {
+    "provides-namespace" : true
+  }
+}

ElementX/SupportingFiles/target.yml

@@ -60,6 +60,16 @@ targets:
         else
             echo "warning: SwiftLint not installed, download from https://github.com/realm/SwiftLint"
         fi
+    - name: 🛠 SwiftGen
+      runOnlyWhenInstalling: false
+      shell: /bin/sh
+      script: |
+        export PATH="$PATH:/opt/homebrew/bin"
+        if which swiftgen >/dev/null; then
+            swiftgen config run --config Tools/SwiftGen/swiftgen-config.yml
+        else
+            echo "warning: SwiftGen not installed, download from https://github.com/SwiftGen/SwiftGen"
+        fi
       
     dependencies:
     - package: MatrixRustSDK