fix(@angular-devkit/build-angular): better handle relative paths with bundleDependencies=false

When `bundleDependencies` is turned off, webpack only bundles modules imported via relative path.
Existing check works well for import paths like `'./some/file'`,
but fails for imports traversing the dir structure up, like `'../some/file'`.

Author: amakhrov

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

@@ -53,7 +53,7 @@ export function getServerConfig(wco: WebpackConfigOptions): Configuration {
       ...externalDependencies,
       (context: string, request: string, callback: (error?: null, result?: string) => void) => {
         // Absolute & Relative paths are not externals
-        if (request.startsWith('./') || isAbsolute(request)) {
+        if (request.startsWith('.') || isAbsolute(request)) {
           callback();
 
           return;