Issue #2273631 by vijaycs85: Unify config entity schemas with a base schema type.

core/config/schema/core.data_types.schema.yml

core/modules/block/config/schema/block.schema.yml

.../block/custom_block/config/schema/custom_block.schema.yml

core/modules/breakpoint/config/schema/breakpoint.schema.yml

core/modules/config/src/Tests/ConfigSchemaTest.php

...ig/tests/config_test/config/schema/config_test.schema.yml

core/modules/contact/config/schema/contact.schema.yml

core/modules/editor/config/schema/editor.schema.yml

core/modules/entity/config/schema/entity.schema.yml

core/modules/field/config/schema/field.schema.yml

core/modules/filter/config/schema/filter.schema.yml

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

core/modules/language/config/schema/language.schema.yml

core/modules/node/config/schema/node.schema.yml

core/modules/rdf/config/schema/rdf.schema.yml

core/modules/search/config/schema/search.schema.yml

core/modules/shortcut/config/schema/shortcut.schema.yml

core/modules/system/config/schema/system.schema.yml

core/modules/taxonomy/config/schema/taxonomy.schema.yml

core/modules/tour/config/schema/tour.schema.yml