Changes:
       ZBX-3783 valuemap.get: added strict validation of input parameters
       
Changes:
       ZBX-11272 alert.get: added support of two new options mediatypeid and sendto in the sortfield parameter
       
Bug fixes:
       ZBX-10861 discoveryrule.create, discoveryrule.update: changed "username" and "password" fields to optional for HTTP agent type discovery rules and using authentication
       
Bug fixes:
       ZBX-10861 httptest.create, httptest.update: changed "http_user" and "http_password" fields to optional when using authentication
       
Bug fixes:
       ZBX-10861 item.create, item.update: changed "username" and "password" fields to optional for HTTP agent type items and using authentication
       
Bug fixes:
       ZBX-10861 itemprototype.create, itemprototype.update: changed "username" and "password" fields to optional for HTTP agent type item prototypes and using authentication