[Contracts] fine tune composer.json declarations for suggest/provide

Author: nicolas-grekas

composer.json

@@ -35,7 +35,7 @@
         "symfony/yaml": "<3.4"
     },
     "provide": {
-        "symfony/translation-contracts": "1.0"
+        "symfony/translation-contracts-implementation": "1.0"
     },
     "suggest": {
         "symfony/config": "",