Add uncategorised cookie category

Replace the `required` boolean column on cookie_categories with a `kind`
enum (NORMAL, NECESSARY, UNCATEGORISED). The Necessary category remains
undeletable and always-on for consent; the new Uncategorised category is
also undeletable but users can opt out of it.

When a category is deleted, its cookies are merged into the Uncategorised
category (lazy-created for legacy banners that don't have one yet).

Signed-off-by: Émile Ré <emile@getprobo.com>

pkg/server/api/console/v1/graphql/cookie_banner.graphql

@@ -90,7 +90,7 @@ type CookieCategory implements Node {
     cookieBanner: CookieBanner @goField(forceResolver: true)
     name: String!
     description: String!
-    required: Boolean!
+    kind: String!
     rank: Int!
     cookies: [CookieItem!]!
     createdAt: Datetime!
@@ -212,7 +212,6 @@ input CreateCookieCategoryInput {
     cookieBannerId: ID!
     name: String!
     description: String!
-    required: Boolean!
     rank: Int!
     cookies: [CookieItemInput!]
 }