show_subports causes error with CellArray references

[tvt173]

Describe the bug
When a cell has a CellArray reference, i.e. added with c.add_array(), and then it is shown with show_subports=True, it throws an error: AttributeError: 'CellArray' object has no attribute 'get_ports_list'

To Reproduce

    c = gf.Component()
    c.add_array(gf.components.straight())
    c.show(show_ports=True, show_subports=True)

Expected behavior
In this case, the reference type is actually a gdspy CellArray, which doesn't have ports, so we should probably just skip the references which are not of type ComponentReference.

Suggested fix
On line 1231 of component.py, only call add_pins_triangle() if the reference is of type ComponentReference

[joamatab]

Thank you Troy!

fixed here
#794