refactor(schematics): remove unused imports in templates (#12752)

* Removes unused imports in the `address-form` and `nav` schematic.

Author: devversion

src/lib/schematics/address-form/files/__path__/__name@dasherize@if-flat__/__name@dasherize__.component.ts

@@ -1,4 +1,4 @@
-import { Component, ViewChild<% if(!!viewEncapsulation) { %>, ViewEncapsulation<% }%><% if(changeDetection !== 'Default') { %>, ChangeDetectionStrategy<% }%> } from '@angular/core';
+import { Component<% if(!!viewEncapsulation) { %>, ViewEncapsulation<% }%><% if(changeDetection !== 'Default') { %>, ChangeDetectionStrategy<% }%> } from '@angular/core';
 import { FormBuilder, Validators } from '@angular/forms';
 
 @Component({

src/lib/schematics/nav/files/__path__/__name@dasherize@if-flat__/__name@dasherize__.component.ts

@@ -1,5 +1,5 @@
 import { Component<% if(!!viewEncapsulation) { %>, ViewEncapsulation<% }%><% if(changeDetection !== 'Default') { %>, ChangeDetectionStrategy<% }%> } from '@angular/core';
-import { BreakpointObserver, Breakpoints, BreakpointState } from '@angular/cdk/layout';
+import { BreakpointObserver, Breakpoints } from '@angular/cdk/layout';
 import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';