[FEATURE] Improve error message at login

[Danny-dK]

When users want to login to Yoda but actually have not been added to a folder in Yoda, the error message is less helpful for the user

Describe the solution you'd like

I wonder if it would be possible for the system to check whether an email address exists or not and give the error message "Username not recognized. You have not been added to any resources in Yoda, please request access from your Yoda data manager" or something similar like that. When a username has been recognized, the error message could be "invalid password".

Describe alternatives you've considered

If it would take too many resources to first check whether a user exists, perhaps changing the message to "Login has failed. It could be that you haven't been given access yet or that your username or password was misspelled. Please try again or contact your Yoda data manager of your group.".... or something similar or shorter.