ENH: Connector Element Export

### Enhancement Description

Hello,

There is a "Connector Element" category in Revit (OST_ConnectorElem // -2007000).

These are used to create connections for HVAC equipment.

Unfortunately, it's currently impossible to control whether these elements are exported to IFC. They are not shown in the "Visibility/Graphics" settings or the IFC "Category Mapping Table" and are always exported by default as IfcDistributionPort.

As these are not heavily used in the early stages of a project, they cause IFC files to become bloated, with thousands of instances within a single file with no particular benefit.

Would it be possible to add the ability to control whether these elements are exported? A second, subsequent improvement might be to allow better control by adding them as a standalone category within Revit.

### Revit Version

2026.0.x

### IFC for Revit Addon Version

26.1.0

### Windows Version

11 24H2

No files or tests are named. Start by locating the export handling for Revit's OST_ConnectorElem category and its IfcDistributionPort output, then review how Visibility/Graphics and the IFC Category Mapping Table control other categories. Done means providing a documented way to include or exclude Connector Elements from IFC export without affecting other categories.

Written by the indexing model from the issue text.