collab: Clean up LLM token creation (#26955)

This PR cleans up the LLM token creation a bit.

We now pass in the entire list of feature flags to the
`LlmTokenClaims::create` method to prevent having a bunch of confusable
`bool` parameters.

Release Notes:

- N/A

crates/collab/src/db/tables/user.rs

@@ -43,6 +43,20 @@ pub enum Relation {
     Contributor,
 }
 
+impl Model {
+    /// Returns the timestamp of when the user's account was created.
+    ///
+    /// This will be the earlier of the `created_at` and `github_user_created_at` timestamps.
+    pub fn account_created_at(&self) -> NaiveDateTime {
+        let mut account_created_at = self.created_at;
+        if let Some(github_created_at) = self.github_user_created_at {
+            account_created_at = account_created_at.min(github_created_at);
+        }
+
+        account_created_at
+    }
+}
+
 impl Related<super::access_token::Entity> for Entity {
     fn to() -> RelationDef {
         Relation::AccessToken.def()