Remove SELECT * from edit/initialize Query (#288)

* Major refactor of EditDataMetadata providers

* EditMetadataFactory generates "basic" EditTableMetadata objects based entirely on SMO metadata
* SmoEditTableMetadata no longer depends on SMO, making it unecessary to mock it
* Renamed SmoEditTableMetadata to EditTableMetadata
* EditTableMetadata can be extended with DbColumnWrappers

* Moving logic for extending a EditColumnMetadata into that class

* I *think* this will work for async execution of initialize tasks

* Fixing unit tests for new Edit(Table|Column)Metadata classes

* Async stuff that works! And passes unit tests

* Adding unit tests
Adding .idea to gitignore

* Adding message to the EditSessionReadyEvent

* Fixes from dev merge

* Fixing unit tests that Rider didn't catch as failing
May have been a bit heavy-handed with the async/await stuff

* Couple changes as per PR comments

src/Microsoft.SqlTools.ServiceLayer/EditData/UpdateManagement/RowUpdate.cs

@@ -39,7 +39,7 @@ namespace Microsoft.SqlTools.ServiceLayer.EditData.UpdateManagement
         /// <param name="rowId">Internal ID of the row that will be updated with this object</param>
         /// <param name="associatedResultSet">Result set for the rows of the object to update</param>
         /// <param name="associatedMetadata">Metadata provider for the object to update</param>
-        public RowUpdate(long rowId, ResultSet associatedResultSet, IEditTableMetadata associatedMetadata)
+        public RowUpdate(long rowId, ResultSet associatedResultSet, EditTableMetadata associatedMetadata)
             : base(rowId, associatedResultSet, associatedMetadata)
         {
             cellUpdates = new ConcurrentDictionary<int, CellUpdate>();