Feat: Default organization slug for LDAP/SAML

[DanielHougaard]

Description 📣

Main

We now have a way of setting the default slug as a part of the admin settings / server configuration. When the default org slug is set, a few things will happen:

1. When attempting to log in with LDAP, the org slug input field will be hidden from the user, and the value will be pre-set to the default organization slug.
2. When logging in with SAML and the default org slug is set, it will entirely skip the org slug input page, and take you straight to the SAML auth.
3. If the default org slug is set, you'll never be asked to "select an organization". It will assume you're trying to log into the default organization and automatically select the default organization.

Technical:
Instead of storing the organization slug as text in the database, we're storing a reference to the organization itself by ID. This will allow cascading to work, and I generally believe we should always be keeping references instead of just plain text when we're keeping track of resources.

Minor:

1. Fixed a type mismatch

Type ✨

• Bug fix
• New feature
• Breaking change
• Documentation

Tests 🛠️

# Here's some code block to paste some code snippets

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• I have read the contributing guide, agreed and acknowledged the code of conduct. 📝

[maidul98]

I see what you are doing. User enters slug, and you take the slug and get it's id and save the id and when we get the admin config, we returns the id and the associated slug.

I just remembered, one of the friction points i observed watching customer do this is not knowing where the org slug is located at since it is their first time setting things up. I think it will be a better experience if they can just select a org from a drop down (we already have a API for getting users orgs) and then we send the id to the DB and save as is. When we fetch admin config, we can compute org slug as you do now. This way, saving is identical to before too

Looks good to me.

Dismissing since handing it over to @maidul98

[maidul98]

FYI, tried to load things up with a fresh DB and the migration that creates the instance row in the DB doesn't get created so the APIs throw error when it calls get config

[maidul98]

lgtm, let's definitely test in gamma since this not working will impact logins for enterprises