Issue #3425870 by phenaproxima, alexpott, Wim Leers: Add validation constraints to image.settings

core/lib/Drupal/Core/Validation/ConstraintManager.php

core/modules/forum/tests/fixtures/drupal7.php

core/modules/image/config/schema/image.schema.yml

.../tests/src/Kernel/Migrate/d7/MigrateImageSettingsTest.php

...s/image/tests/src/Kernel/SettingsConfigValidationTest.php

core/modules/migrate_drupal/tests/fixtures/drupal7.php

core/modules/statistics/tests/fixtures/drupal7.php

core/modules/tracker/tests/fixtures/drupal7.php