Add default board to new projects, remove uncategorized pseudo-board (#29874)

On creation of an empty project (no template) a default board will be
created instead of falling back to the uneditable pseudo-board.

Every project now has to have exactly one default boards. As a
consequence, you cannot unset a board as default, instead you have to
set another board as default. Existing projects will be modified using a
cron job, additionally this check will run every midnight by default.

Deleting the default board is not allowed, you have to set another board
as default to do it.

Fixes #29873
Fixes #14679 along the way
Fixes #29853

Co-authored-by: delvh <dev.lh@web.de>

models/migrations/fixtures/Test_CheckProjectColumnsConsistency/project.yml

@@ -0,0 +1,23 @@
+-
+  id: 1
+  title: project without default column
+  owner_id: 2
+  repo_id: 0
+  is_closed: false
+  creator_id: 2
+  board_type: 1
+  type: 2
+  created_unix: 1688973000
+  updated_unix: 1688973000
+
+-
+  id: 2
+  title: project with multiple default columns
+  owner_id: 2
+  repo_id: 0
+  is_closed: false
+  creator_id: 2
+  board_type: 1
+  type: 2
+  created_unix: 1688973000
+  updated_unix: 1688973000

models/migrations/fixtures/Test_CheckProjectColumnsConsistency/project_board.yml

@@ -0,0 +1,26 @@
+-
+  id: 1
+  project_id: 1
+  title: Done
+  creator_id: 2
+  default: false
+  created_unix: 1588117528
+  updated_unix: 1588117528
+
+-
+  id: 2
+  project_id: 2
+  title: Backlog
+  creator_id: 2
+  default: true
+  created_unix: 1588117528
+  updated_unix: 1588117528
+
+-
+  id: 3
+  project_id: 2
+  title: Uncategorized
+  creator_id: 2
+  default: true
+  created_unix: 1588117528
+  updated_unix: 1588117528