Return context after it has been generated (#2194)

* Emit generate scripts complete event to client

* Rename Message to ErrorMessage

* Sets owner URI for complete params obj

* Setting complete flag explicitly

* Making errorMessage prop nullable

* Localizes error messages

* Return context scripts and remove script tabs

* Send event when script gen isn't needed

* Change notification to request endpoint

* test get context when context doesn't exist

* Stop reading old context files

src/Microsoft.SqlTools.ServiceLayer/Localization/sr.strings

@@ -188,6 +188,13 @@ ParsingErrorHeader (int lineNumber, int columnNumber) = Line {0}, column {1}
 
 ScriptTooLarge (int maxChars, int currentChars) = The current script is too large for Parameterization for Always Encrypted, please disable Parameterization for Always Encrypted in Query Options (Query > Query Options > Execution > Advanced). Maximum allowable length: {0} characters, Current script length: {1} characters
 
+############################################################################
+# Server Contextualization Service
+
+WritingServerContextualizationToCacheError (string message) = An error was encountered while writing server contextualization scripts to the cache. Error: {0}
+
+FailedToGenerateServerContextualizationScripts = Failed to generate server contextualization scripts
+
 ############################################################################
 # Serialization Service