Add a quick fix to remove unused params, vars, and fields

[webspam]

Features

• Unused parameters, local variables, and fields now offer a "Remove unused" quick fix that deletes the binding for you
• When a name is part of a grouped declaration, only that name and its comma are removed, leaving the rest intact even across multiple lines
• Removing a field also clears any leftover default and defaults { ... } entries that referenced it

Refactoring

• Extracts a shared remove_list_entry helper for deleting one entry from a comma-separated list; inline-variable removal now reuses it and gains the same multi-line cleanup