feat(MatDialog): Accept a function on MatDialogRef's disableClose

[robmv]

Feature Description

Currently MatDialogRef's disableClose type is boolean | undefined. Allow another function type like () => boolean in order to have dynamic checks before processing the ESC key or clicking outside the dialog.

Use Case

The most use I have of disableClose is to disable it when a form is dirty. As there is no event yet on Angular for the dirty state, I have to resort to:

 ngDoCheck(): void {
    // WORKAROUND Remove when there are proper events for dirty status changes
    this.dialogRef.disableClose = this.form.dirty;
  }

It would help a lot if disableClose could be function that can check, in my case, the form dirty state and that way remove the DoCheck lifecycle event.