fix(cdk/text-field): Long multiline textfield focus issue

When we have long multiline textfield and put cursor on almost an end (For eg. on 3rd last line) the scroll moves up to the top of textarea. This fix will cache the `scrollTop` in `resizeToFitContent` method

Fixes #20255

Author: mistrykaran91

src/cdk/text-field/autosize.ts

@@ -47,6 +47,7 @@ export class CdkTextareaAutosize implements AfterViewInit, DoCheck, OnDestroy {
 
   /** Keep track of the previous textarea value to avoid resizing when the value hasn't changed. */
   private _previousValue?: string;
+  private _currentScrollTop: number;
   private _initialHeight: string | undefined;
   private readonly _destroyed = new Subject<void>();
   private _listenerCleanups: (() => void)[] | undefined;
@@ -303,6 +304,7 @@ export class CdkTextareaAutosize implements AfterViewInit, DoCheck, OnDestroy {
 
     this._cacheTextareaLineHeight();
     this._cacheTextareaPlaceholderHeight();
+    this._currentScrollTop = this._textareaElement.scrollTop;
 
     // If we haven't determined the line-height yet, we know we're still hidden and there's no point
     // in checking the height of the textarea.
@@ -367,6 +369,7 @@ export class CdkTextareaAutosize implements AfterViewInit, DoCheck, OnDestroy {
     // it to receive focus on IE and Edge.
     if (!this._destroyed.isStopped && this._hasFocus) {
       textarea.setSelectionRange(selectionStart, selectionEnd);
+      textarea.scrollTop = this._currentScrollTop;
     }
   }
 }