Bad Autocompletion on resource types after `.` or `/`

**Bicep version**
v0.4.1124

**Describe the bug**
When typing a resource name in auto completion, auto complete seems to forget everything you've typed so far if you get to a `.` or a `/`, which leads to some surprising completion results.

**To Reproduce**

Now type `/w`. I'd now expect `Microsoft.OperationalInsights/workspace` to be the top result. Instead you end up with completely unrelated results. It seems as if auto completion is ignoring everything before the `/` and just searching on `w`


Reproduce the autocomplete steps in the issue using Bicep v0.4.1124, including completion after a resource type's `.` and `/`. Trace which autocomplete search input is used for the typed resource name, then verify that the full prefix affects the results and places `Microsoft.OperationalInsights/workspace` first for `/w`.

Written by the indexing model from the issue text.