[Epic] Improve handling for user name null cases and syncs

[adam-james-v]

There are some important gaps in how we handle SSO login names at the moment. This project aims to tackle two semi-related issues:

• We sync new SSO user details and attributes for users on the initial and subsequent logins. For the user’s name specifically (not an issue for other attributes), we sync on initial login but then we don’t update it in subsequent logins. This causes any name-related changes made from the SSO provider to not be updated in Metabase.
• If a Metabase user's SSO provider does not supply us with a first/last name, we auto-fill Unknown in these cases. This causes weird cases in the product where we refer to people by their first name.

This project will fix the syncing bug and improve the implementation and UI regarding first and last names.

Links

• product doc (Notion)
• feature branch: TBD
• Issue links:
  • SSO logins doesn't update user name in Metabase #15484
  • Better handling for SSO users without first or last names #16158

Implementation Plan
The linked issues can be handled independently, even though they are related. So, we'll tackle each as a separate milestone.

Milestone 1: Proper user name sync
This milestone is backend only

• fix the syncing bug
• unit tests to check that SSO details are synced

Milestone 2: Better Handling for unknown user names
backend:

• allow nil first and last names in backend
• fix logic for :common_name
• appropriate unit tests

frontend:

• List places where null user names need to be handled.
  • user.common_name
  • user.first_name
  • user.last_name
  • user.getName()
• Create special cases in the frontend handling null user name. And use user email in places that require value.
  • user.common_name
  • user.first_name
  • user.last_name
  • user.getName()

Milestone 3: Relax first/last name requirements on manual account creation
We should relax naming requirements in general. If we allow nil appropriately on the backend, this may be a frontend only milestone.

• Make first/last name fields optional on account creation Make first name and last name optional in user forms #23327
  • Modify type constraint

    metabase/frontend/src/metabase-types/api/user.ts

    Lines 5 to 6 in 9f41e1d

    	first_name: string;
    	last_name: string;

  • Make user form name fields optional

    metabase/frontend/src/metabase/entities/users/forms.js

    Lines 16 to 22 in 9f41e1d

    	validate: validate.required().maxLength(100),
    	},
    	{
    	name: "last_name",
    	title: t`Last name`,
    	placeholder: "Appleseed",
    	validate: validate.required().maxLength(100),

• Fix admin audit doesn't fall back name to email. Audit Queries fall back to email when first/last names are nil #23393
• change the LDAP enterprise enhancement impl to re-use the JWT/SAML fetch-and-update-user! function — to be completed in Better handling for SSO users without first or last names #16158

How to Test This Feature Out
Follow the instruction here https://www.notion.so/metabase/Improve-handling-for-user-name-null-cases-and-syncs-9b6b3f93500c42d4b3dd019e7389e865