Fix uplevel SQL Server support and differentiate External and FileTable types in object explorer list (#567)

* Differentiate External and FileTable types in object explorer list
- Add (External) and (File Table) to the labels
- Pre-fetch these properties to avoid perf hit

Note on testing: These are both quite hard to initialize, so adding tests to the integration tests would require always having a server with Polybase enabled / FileTable enabled. Given this I feel it should be OK to use manual testing. Long term, we should have unit-level tests that cover the functionality or figure out how to have a perfect pre-configured server and a set of tests to run the breadth of this logic against it.

* Fix handling of vNext servers to default to latest known version
- Default uplevel / unknown versions to the latest version
- In the IsValidFor check also just see if the server version registers as "All" since this is the default for unknown servers. This is a backup handler, the 1st fix is the primary one

src/Microsoft.SqlTools.ServiceLayer/Localization/sr.ru.resx

@@ -87,11 +87,11 @@
   <data name="EE_ScriptError_Error"><value>Произошла ошибка сценария.</value></data>
   <data name="EE_ScriptError_ParsingSyntax"><value>Обнаружен неправильный синтаксис при обработке {0}.</value></data>
   <data name="EE_ScriptError_FatalError"><value>Произошла неустранимая ошибка.</value></data>
-  <data name="EE_ExecutionInfo_FinalizingLoop"><value>Выполнено {0} раз...</value></data>
+  <data name="EE_ExecutionInfo_FinalizingLoop"><value>Выполнение завершено такое количество раз: {0}...</value></data>
   <data name="EE_ExecutionInfo_QueryCancelledbyUser"><value>Пользователь отменил запрос.</value></data>
   <data name="EE_BatchExecutionError_Halting"><value>При выполнении пакета произошла ошибка.</value></data>
   <data name="EE_BatchExecutionError_Ignoring"><value>В процессе выполнения пакета произошла ошибка, но она была проигнорирована.</value></data>
-  <data name="EE_ExecutionInfo_InitializingLoop"><value>Начало цикла выполнения {0} раз...</value></data>
+  <data name="EE_ExecutionInfo_InitializingLoop"><value>Beginning execution loop</value></data>
   <data name="EE_ExecutionError_CommandNotSupported"><value>Команда {0} не поддерживается.</value></data>
   <data name="EE_ExecutionError_VariableNotFound"><value>Переменная {0} не найдена.</value></data>
   <data name="BatchParserWrapperExecutionEngineError"><value>Ошибка выполнения SQL: {0}</value></data>