Add Chromium Canary target

The mv3 variant will be used for this target, to start testing it.

Bug: translateselectedtext:10
Change-Id: I0bc5d715d03b2ef9a7514e107d56c66703f05060
diff --git a/webpack.config.js b/webpack.config.js
index c66738d..ec70593 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -20,6 +20,7 @@
       params: {
         browser_target: env.browser_target,
         production: args.mode == 'production',
+        canary: !!env.canary,
       },
     },
   };
@@ -43,7 +44,8 @@
       new CopyWebpackPlugin({
         patterns: [
           {
-            from: path.join(__dirname, 'src/icons'),
+            from: path.join(
+                __dirname, 'src/icons', env.canary ? 'canary' : 'regular'),
             to: path.join(outputPath, 'icons'),
           },
         ]