Debugger: Variables inspector should not unselect when releasing filter

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> In a long list of variables it's sometimes helpful to drill down on a variable name in order to quickly inspect a certain variable. Using the filter feature of the Variables view, it's easy to do that. However, while the filter is active, it's not possible to inspect a structured object variables content. And then, when you release the filter, the previously selected variable becomes unselected – making it hard to find the variable back again in the long list of variables:  I propose to either not apply the filter to structured objects' members in Variables inspector or to refrain from unselecting a previously made selection when the filter is released.