Micro-optimization: Remove unused resources

[kevingamez]

Its impact is confined to the organization and readability of the code rather than addressing broader performance concerns. In the case of removing unused imports, the objective is to create a more concise and maintainable codebase. By eliminating unnecessary dependencies, developers ensure that the code remains clear and comprehensible.

This unused imports are presented in in accounts_sheet.dart, avatar.dart, send_complete_sheet.dart, appstate_container.dart, settings_drawer.dart and nanoutil.dart, there are imports that are not being used.