Clean up unused imports

As of version 19, Angular reports when a component's imports array contains symbols that aren't used in its template.

Running this schematic will clean up all unused imports within the project.

Run the schematic using the following command:

      ng generate @angular/core:cleanup-unused-imports

Before

      import { Component } from '@angular/core';import { UnusedDirective } from './unused';@Component({  template: 'Hello',  imports: [UnusedDirective],})export class MyComp {}

After

      import { Component } from '@angular/core';@Component({  template: 'Hello',  imports: [],})export class MyComp {}