Refactoring LoginActivity and other improvements. (#561)

Adding error message for login().

Final touch.

Refactoring LoginActivity and other improvements.

Co-authored-by: opyale <opyale@noreply.gitea.io>
Reviewed-on: https://codeberg.org/gitnex/GitNex/pulls/561
Reviewed-by: 6543 <6543@noreply.codeberg.org>

.editorconfig

@@ -20,3 +20,7 @@ indent_size = 2
 
 [{*.yml,*.yaml}]
 indent_size = 2
+
+[*.md]
+trim_trailing_whitespace = false
+insert_final_newline = false