refactor(cdk/table): move virtual scrolling logic into the table

Combines the logic from the `CdkTableVirtualScroll` with the existing `CdkTable`. This allows us to remove the following steps from the virtual scrolling setup:
1. Having to import `CdkTableVirtualScroll`.
2. Having to set `fixedLayout` on the table.
3. Having to set `virtualScroll` on the table.

Author: crisbeto

src/cdk/table/public-api.ts

@@ -13,7 +13,6 @@ export * from './table-module';
 export * from './sticky-position-listener';
 export * from './text-column';
 export * from './tokens';
-export * from './table-virtual-scroll';
 
 /** Re-export DataSource for a more intuitive experience for users of just the table. */
 export {DataSource} from '../collections';

src/cdk/table/table-module.ts

@@ -36,7 +36,6 @@ import {
 } from './cell';
 import {CdkTextColumn} from './text-column';
 import {ScrollingModule} from '../scrolling';
-import {CdkTableVirtualScroll} from './table-virtual-scroll';
 
 const EXPORTED_DECLARATIONS = [
   CdkTable,
@@ -61,7 +60,6 @@ const EXPORTED_DECLARATIONS = [
   CdkNoDataRow,
   CdkRecycleRows,
   NoDataRowOutlet,
-  CdkTableVirtualScroll,
 ];
 
 @NgModule({