Added text as a required property in sentenceSentiment (Azure#10179)

For stable/v3.0/TextAnalytics.json, added text as a required property in sentenceSentiment.

Author: suhas92

specification/cognitiveservices/data-plane/TextAnalytics/stable/v3.0/TextAnalytics.json

@@ -663,7 +663,8 @@
         "sentiment",
         "confidenceScores",
         "offset",
-        "length"
+        "length",
+        "text"
       ],
       "properties": {
         "text": {