refactor: remove ViewportRuler and ScrollDispatcher exports from overlay (#13047)

Along the same lines as #12871. Replaces the imports for `ViewportRuler` and `ScrollDispatcher` with ones pointing directly to `cdk/scrolling`, rather than going through `cdk/overlay`.

Author: crisbeto

src/cdk/overlay/position/flexible-connected-position-strategy.spec.ts

@@ -1,5 +1,5 @@
 import {ComponentPortal, PortalModule} from '@angular/cdk/portal';
-import {CdkScrollable, ScrollingModule} from '@angular/cdk/scrolling';
+import {CdkScrollable, ScrollingModule, ViewportRuler} from '@angular/cdk/scrolling';
 import {MockNgZone} from '@angular/cdk/testing';
 import {Component, ElementRef, NgModule, NgZone} from '@angular/core';
 import {inject, TestBed} from '@angular/core/testing';
@@ -13,7 +13,6 @@ import {
   OverlayContainer,
   OverlayModule,
   OverlayRef,
-  ViewportRuler,
 } from '../index';
 
 

src/lib/autocomplete/autocomplete-trigger.ts

@@ -14,7 +14,6 @@ import {
   OverlayRef,
   PositionStrategy,
   ScrollStrategy,
-  ViewportRuler,
 } from '@angular/cdk/overlay';
 import {TemplatePortal} from '@angular/cdk/portal';
 import {DOCUMENT} from '@angular/common';
@@ -33,6 +32,7 @@ import {
   Optional,
   ViewContainerRef,
 } from '@angular/core';
+import {ViewportRuler} from '@angular/cdk/scrolling';
 import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
 import {
   _countGroupLabelsBeforeOption,

src/lib/bottom-sheet/bottom-sheet.spec.ts

@@ -1,6 +1,7 @@
 import {Directionality} from '@angular/cdk/bidi';
 import {A, ESCAPE} from '@angular/cdk/keycodes';
-import {OverlayContainer, ViewportRuler} from '@angular/cdk/overlay';
+import {OverlayContainer} from '@angular/cdk/overlay';
+import {ViewportRuler} from '@angular/cdk/scrolling';
 import {dispatchKeyboardEvent} from '@angular/cdk/testing';
 import {
   Component,

src/lib/datepicker/datepicker.spec.ts

@@ -1,5 +1,6 @@
 import {ENTER, ESCAPE, RIGHT_ARROW, UP_ARROW, DOWN_ARROW} from '@angular/cdk/keycodes';
-import {Overlay, OverlayContainer, ScrollDispatcher} from '@angular/cdk/overlay';
+import {Overlay, OverlayContainer} from '@angular/cdk/overlay';
+import {ScrollDispatcher} from '@angular/cdk/scrolling';
 import {
   createKeyboardEvent,
   dispatchEvent,

src/lib/dialog/dialog.spec.ts

@@ -24,7 +24,8 @@ import {Location} from '@angular/common';
 import {SpyLocation} from '@angular/common/testing';
 import {Directionality} from '@angular/cdk/bidi';
 import {MatDialogContainer} from './dialog-container';
-import {OverlayContainer, ScrollStrategy, ScrollDispatcher, Overlay} from '@angular/cdk/overlay';
+import {OverlayContainer, ScrollStrategy, Overlay} from '@angular/cdk/overlay';
+import {ScrollDispatcher} from '@angular/cdk/scrolling';
 import {A, ESCAPE} from '@angular/cdk/keycodes';
 import {dispatchKeyboardEvent} from '@angular/cdk/testing';
 import {

src/lib/select/select.ts

@@ -26,8 +26,8 @@ import {
   Overlay,
   RepositionScrollStrategy,
   ScrollStrategy,
-  ViewportRuler,
 } from '@angular/cdk/overlay';
+import {ViewportRuler} from '@angular/cdk/scrolling';
 import {
   AfterContentInit,
   Attribute,

src/lib/tooltip/tooltip.ts

@@ -18,10 +18,10 @@ import {
   Overlay,
   OverlayConnectionPosition,
   OverlayRef,
-  ScrollDispatcher,
   ScrollStrategy,
   VerticalConnectionPos,
 } from '@angular/cdk/overlay';
+import {ScrollDispatcher} from '@angular/cdk/scrolling';
 import {Platform} from '@angular/cdk/platform';
 import {ComponentPortal} from '@angular/cdk/portal';
 import {take, takeUntil} from 'rxjs/operators';