Show all CloudFormation stacks in Explorer

The toolkit currently only shows CloudFormation stacks with a state of `'CREATE_COMPLETE' or 'UPDATE_COMPLETE'` that contain lambda functions. It should show almost all of the stacks instead. This should be made consistent with the Jetbrains Toolkit, which shows a wider set of CloudFormation stacks (update this issue when that criteria is known).

Acceptance Criteria:
* All CloudFormation stacks are shown in the Explorer, as long as they belong to one of the following states: (TBD)

Start by comparing the CloudFormation stack criteria used by the VS Code Explorer with the wider set shown by the JetBrains Toolkit. Confirm the allowed stack states and update the issue's acceptance criteria; the work is complete when the Explorer shows all stacks matching those agreed states, rather than only stacks with Lambda functions.

Written by the indexing model from the issue text.