Notebook fixes: Fix #4129, fix #4116, Fix #3913, fix empty results error (#4150)

- Fixes #4129 Overlapping command help windows in notebook
  - Do not show parameter hints for inactive cells, to avoid them hanging around when no longer selected
- Fixes #4116 Notebooks: Intellisense Doesn't Work using Add New Connection
  - Move connect/disconnect logic to 1 place (code component) instead of 2
  - Handle the case where you connect after choosing active cell. We now hook to the event and update connection
- Fix issues in sql session manager where result outputs 0 rows. This was failing to show the empty resultset contents, which is a regression vs. query editor. It also put unhandled error on the debug console
- Fix #3913 Notebook: words selected in other cells should be unselected on cell change

Note: after fix, now looks as follows. Need to do follow up to get correct grid min height

![image](https://user-images.githubusercontent.com/10819925/53280226-9e629580-36cc-11e9-8f40-59cd913caeee.png)

src/sql/parts/modelComponents/queryTextEditor.ts

@@ -81,6 +81,8 @@ export class QueryTextEditor extends BaseTextEditor {
 			options.hideCursorInOverviewRuler = true;
 			if (!this._selected) {
 				options.renderLineHighlight = 'none';
+				options.parameterHints = { enabled: false };
+				options.matchBrackets = false;
 			}
 			if (this._hideLineNumbers) {
 				options.lineNumbers = 'off';