Issue #2351729: Use right name for container test.
Issue #2351729: Copy CacheContext related files from Drupal 8.
Issue #2351729: Add render_cache version of CacheContexts.
Issue #2351729: Add some basic cache contexts test coverage.
Issue #2351729: Add cache context definitions to the DIC.
Issue #2351729: Add mockery listeners.
Issue #2351729: once() does not work properly.
Issue #2351729: Add CachedContainerBuilder class.
Issue #2351729: Add test coverage for CachedContainerBuilder.
Issue #2351729: Add static init function.