SwiftGen: Handle MatrixKit strings.

Tools/SwiftGen/swiftgen-config.yml

@@ -16,6 +16,14 @@ strings:
     params:
       className: VectorL10n
       publicAccess: true
+strings:
+  inputs: Modules/MatrixKit/Assets/MatrixKitAssets.bundle/en.lproj/MatrixKit.strings
+  outputs:
+    templatePath: Templates/Strings/flat-swift4-vector.stencil
+    output: MatrixKitStrings.swift
+    params:
+      className: MatrixKitL10n
+      publicAccess: true
 xcassets:  
   inputs:
     - Assets/Images.xcassets