Insert resource should allow users to create new bicep file from command pallet

**Is your feature request related to a problem? Please describe.**
The insert resource command allows me to insert a resource to the active editor or an existing bicep file. I would like to see the option to create a new file directly when using the command instead of having to first create a file and then insert the resource.

**Describe the solution you'd like**
If no active editor is open I would like to see the option to create a new bicep file in the drop down when using the insert resource function.

Start by locating the insert resource command and its command-palette handling in the Bicep project. Trace how it chooses between the active editor and an existing Bicep file; done means that, with no active editor, the command offers creation of a new Bicep file and inserts the resource into it.

Written by the indexing model from the issue text.