Ensure Consistent Category Colors (#1722)

* feat: add validation to require consistent category color

* feat: reflect color requirement in new category form

* refactor: move logic inline over shared component

* rubocop

* tests: fix breaking and add case for new validation

* feat: hide color selector when parent category selected

* feat: override color with parent color in model

* tests: remove case for unnecessary validation

---------

Signed-off-by: Julien Bertazzo Lambert <42924425+JLambertazzo@users.noreply.github.com>

test/models/category_test.rb

@@ -25,7 +25,7 @@ class CategoryTest < ActiveSupport::TestCase
     category = categories(:subcategory)
 
     error = assert_raises(ActiveRecord::RecordInvalid) do
-      category.subcategories.create!(name: "Invalid category", color: "#000", family: @family)
+      category.subcategories.create!(name: "Invalid category", family: @family)
     end
 
     assert_equal "Validation failed: Parent can't have more than 2 levels of subcategories", error.message