fix(@angular-devkit/build-angular): override already existing assets in compilation

With this change we align the copying of assets between `ng build` and `ng serve`. Previously in `ng serve` already copied assets where not overridden.

More info: https://webpack.js.org/plugins/copy-webpack-plugin/#force

Closes #18787

(cherry picked from commit 4d2f4ec)

Author: alan-agius4

packages/angular_devkit/build_angular/src/angular-cli-files/models/webpack-configs/common.ts

@@ -270,6 +270,7 @@ export function getCommonConfig(wco: WebpackConfigOptions): Configuration {
         to: output.replace(/^\//, ''),
         from: glob,
         noErrorOnMissing: true,
+        force: true,
         globOptions: {
           dot: true,
           ignore: [