Don't perform currency translation imports during config sync

When (re-)installing an exported site configuration containing currency translations (inside the sync/language directory), the associated currency is imported, and Commerce Price module responds in commerce_price_configurable_language_insert() by importing a translation. Later, the config importer attempts to RE-create the translation, throwing an error.

This patch adds a simple check on configuration sync status, similar to other checks around Drupal, though most are in install hooks.