server: make attributes names, group names and emails case insensitive

In addition, group names and emails keep their casing

server/src/domain/sql_backend_handler.rs

@@ -87,7 +87,7 @@ pub mod tests {
         handler
             .create_user(CreateUserRequest {
                 user_id: UserId::new(name),
-                email: format!("{}@bob.bob", name),
+                email: format!("{}@bob.bob", name).into(),
                 display_name: Some("display ".to_string() + name),
                 first_name: Some("first ".to_string() + name),
                 last_name: Some("last ".to_string() + name),
@@ -100,7 +100,7 @@ pub mod tests {
     pub async fn insert_group(handler: &SqlBackendHandler, name: &str) -> GroupId {
         handler
             .create_group(CreateGroupRequest {
-                display_name: name.to_owned(),
+                display_name: name.into(),
                 ..Default::default()
             })
             .await