Do not show the warnings directly but fold it in that can be unfold to see the detail

[unkcpz]

The aiida-registry is now for users as well, the warnings shown in details may scare users out from using the plugin. The warnings were supposed to show to developers to fix the issues that are not proper in the plugin, thus should be more invisible to users.
The solution we agree after discuss with @khsrali is to not show the warnings one by one but fold it in an icon that show the number of warnings and can be unfolded to check the details.

For the errors, we keep it as it is with showing the long traceback since the error means the plugin has problem that either prevent user to use or the entrypoint information are not properly displayed. The errors are for developers to take the action ASAP.