Deployment Pane: Please add jsonc file type support to the parameters file picker

You can only choose json files currently. But since deployments can use jsonc files it would be nice to be able to use the deployment pane with them.

Start from the deployment pane's parameters file picker and inspect how it filters selectable JSON files. Done means jsonc parameter files can be selected alongside json files and used by the deployment pane; add or update coverage for the picker behavior if the relevant tests are identified.

Written by the indexing model from the issue text.