Add Better Stack access review connector

Better Stack exposes team members and pending invitations through its
Uptime API. Wire it as an access-review connector so a Better Stack
team can be reviewed in access-review campaigns.

Better Stack has no third-party OAuth app for listing members (its
OAuth is an end-user MCP sign-in), so the connector authenticates with
a Bearer API token plus the team name that scopes the team-members
listing. The driver paginates /api/v2/team-members, maps roles and
invitation records into account records, and the source name is
resolved from the configured team.

This wires the full surface: the provider enum and migration, the
connector settings, the registry registration with the team-name extra
setting, the GraphQL input and resolver marshaling, the frontend field
mapping and connector logo, and cassette-backed driver tests.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

apps/console/src/pages/organizations/access-reviews/dialogs/AddAccessSourceDialog.tsx

@@ -148,6 +148,9 @@ function mapAPIKeyExtraSettingToField(
     case "OKTA":
       if (settingKey === "domain") return "oktaDomain";
       break;
+    case "BETTER_STACK":
+      if (settingKey === "teamName") return "betterStackTeamName";
+      break;
   }
   return null;
 }