Fix issues in fetchSchema for OpenCypher (#245)

* Add tests for fetchSchema in OpenCypher

* Fix fetchSchema when edge has no props

Some OpenCypher labels have no edges, but we were assuming they all did. This caused a null reference exception.

I changed the assumption to allow for empty edges and added a guard check to skip empty labels.

* Fix fetchSchema where edge labels is not an array

* Remove todo

* Fix failing test

* Remove unused result variable declaration

* Add .gitignore to /package/graph-explorer

* Remove console logging

* Add more tests, fix edge labels and counts

* Update packages/graph-explorer/.gitignore

Co-authored-by: Alexey Temnikov <alexey.temnikov@improving.com>

---------

Co-authored-by: Alexey Temnikov <alexey.temnikov@improving.com>

packages/graph-explorer/.gitignore

@@ -0,0 +1,2 @@
+node_modules/
+coverage/