Deprecations removal. Drupal 9 readiness

Per a Slack discussion with Gábor Hojtsy regarding usage of D9 tags (Drupal 9, Drupal 9 compatibility, Drupal 9 readiness, etc.), "Drupal 9 compatibility" should be used for contributed projects that need updating and "Drupal 9" was the old tag for D8 issues before the D9 branch was ready. Doing tag cleanup here based on that discussion.

Please review the patch file. Solved Drupal9 readiness. Thank you

@Suresh Prabhu Parkala, Please change the line before apply patch #6, "core_version_requirement: 8^ || 9^" into "core_version_requirement: ^8 || ^9".

After changes done in patch #6 and applied please add the line "core_version_requirement: ^8 || ^9" in data_search.info.yml

Sorry about that. Here is the updated patch please review.

patch #8 works fine.
Thanks, @Suresh Prabhu Parkala

Since we have patches related to general module Drupal 9 readiness it make sense to update issue summary

After I applied patch #8 I see following deprecation notices in project

Warning: The use statement with non-compound name 'Drupal' has no effect in /var/www/build/docroot/modules/contrib/data/data_search/data_search.module on line 3
 27/27 [▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓] 100%

 ------ --------------------------------------------------------------------------- 
  Line   includes/DataHandler.inc                                                   
 ------ --------------------------------------------------------------------------- 
  50     Call to deprecated function db_escape_table():                             
         in drupal:8.0.0 and is removed from drupal:9.0.0. Instead,                 
           get a database connection injected into your service from the container  
           and call escapeTable() on it. For example,                               
           $injected_database->escapeTable($table);                                 
  50     Call to deprecated function db_escape_table():                             
         in drupal:8.0.0 and is removed from drupal:9.0.0. Instead,                 
           get a database connection injected into your service from the container  
           and call escapeTable() on it. For example,                               
           $injected_database->escapeTable($table);                                 
  50     Call to deprecated function db_select():                                   
         in drupal:8.0.0 and is removed from drupal:9.0.0. Instead, get             
           a database connection injected into your service from the container and  
           call select() on it. For example,                                        
           $injected_database->select($table, $alias, $options);                    
  146    Call to deprecated function db_delete():                                   
         in drupal:8.0.0 and is removed from drupal:9.0.0. Instead, get             
           a database connection injected into your service from the container and  
           call delete() on it. For example,                                        
           $injected_database->delete($table, $options);                            
  172    Call to deprecated function db_escape_table():                             
         in drupal:8.0.0 and is removed from drupal:9.0.0. Instead,                 
           get a database connection injected into your service from the container  
           and call escapeTable() on it. For example,                               
           $injected_database->escapeTable($table);                                 
  172    Call to deprecated function db_query():                                    
         in drupal:8.0.0 and is removed from drupal:9.0.0. Instead,                 
           get a database connection injected into your service from the container  
           and call query() on it. For example,                                     
           $injected_database->query($query, $args, $options);                      
 ------ --------------------------------------------------------------------------- 

 ------ -------------------------------------------------------------------- 
  Line   tests/data.test.inc                                                 
 ------ -------------------------------------------------------------------- 
         Reflection error: DrupalWebTestCase not found.                      
         💡 Learn more at https://phpstan.org/user-guide/discovering-symbols  
 ------ -------------------------------------------------------------------- 

 [ERROR] Found 7 errors                                             

These notices are harmless.
It looks like legacy code from Drupal 7 version.
But I think it still should be taken care

Fixed deprecation in #11. Please review

I have added more fixes for deprecated items based on #12 initial changes.