Remove all @deprecated code from Asset component

@Hardik_Patel_12 Can you please add screenshot before and after patch, I checked without patch apply here is no issue in asset.

Thanks @Hardik_Patel_12, for the patch.
@swatichouhan012 FileSystemInterface before Drupal 9.x was optional and is required now
drupal-check somehow did not detect it.

+++ b/core/lib/Drupal/Core/Asset/AssetDumper.php
@@ -80,10 +80,6 @@ public function dump($data, $file_extension) {
   private function getFileSystem() {
-    if (!$this->fileSystem) {
-      @trigger_error('\Drupal\Core\File\FileSystemInterface is a dependency of this class in Drupal 8.7.0 and will be required before Drupal 9.0.0. See https://www.drupal.org/node/3006851.', E_USER_DEPRECATED);
-      $this->fileSystem = \Drupal::service('file_system');
-    }
     return $this->fileSystem;
   }

This whole method can be refactored away now.

This does duplicate some work done in #3104307: Remove BC layers in various Drupal\Core components

There is a remaining @todo in AssetResolver::getCssAssets() - not sure how or when this was deprecated:

    // Allow themes to remove CSS files by CSS files full path and file name.
    // @todo Remove in Drupal 9.0.x.
    if ($stylesheet_remove = $theme_info->getStyleSheetsRemove()) {
      foreach ($css as $key => $options) {
        if (isset($stylesheet_remove[$key])) {
          unset($css[$key]);
        }
      }
    }

I am working on this issue

I was wrong about #10 as this needs properly deprecating in #3069052: Properly deprecate the stylesheets-remove key from theme info.yml files. first, so we can't remove it yet.

Reuploading #9 and marking it RTBC.

+++ b/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php
@@ -67,19 +67,11 @@ class LibraryDiscoveryParser {
-  public function __construct($root, ModuleHandlerInterface $module_handler, ThemeManagerInterface $theme_manager, StreamWrapperManagerInterface $stream_wrapper_manager = NULL, LibrariesDirectoryFileFinder $libraries_directory_file_finder = NULL) {
+  public function __construct($root, ModuleHandlerInterface $module_handler, ThemeManagerInterface $theme_manager, StreamWrapperManagerInterface $stream_wrapper_manager, LibrariesDirectoryFileFinder $libraries_directory_file_finder) {
...
-    if (!$libraries_directory_file_finder) {
-      @trigger_error('Calling LibraryDiscoveryParser::__construct() without the $libraries_directory_file_finder argument is deprecated in drupal:8.9.0. The $libraries_directory_file_finder argument will be required in drupal:10.0.0. See https://www.drupal.org/node/3099614', E_USER_DEPRECATED);
-      $libraries_directory_file_finder = \Drupal::service('library.libraries_directory_file_finder');
-    }

The $libraries_directory_file_finder deprecation stuff shouldn't be removed. This is an 8.9.x deprecation for Drupal 10.

Back to RTBC as remaining method use own issue #3069052: Properly deprecate the stylesheets-remove key from theme info.yml files.

Committed 617441c and pushed to 9.0.x. Thanks!

FILE: ...dev/drupal/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php
----------------------------------------------------------------------
FOUND 1 ERROR AFFECTING 1 LINE
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 434 | ERROR | [x] Expected 1 blank line after function; 2 found
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Fixed on coding standard on commit.