Add Retopology Operators break RF if run via Shift+A menu

[vxlcoder]

Issue #1321 had a secondary issue that I'm capturing here.

The Add Retopology at Cursor / Active Operators through the Shift+A menu instead of the header menu does absolutely nothing. The following error message would be silently reported to the console.

ERROR (wm.operator): source/blender/windowmanager/intern/wm_event_system.cc:1571 wm_operator_invoke: invalid operator call 'RETOPOFLOW_OT_newtarget_cursor'

The issue is due to the operator defining an invoke method but not an execute method.

[vxlcoder]

this issue appears to be fixed now!

Thanks to @JornBoven for helping debug this issue!

You can use this temp link to test it out (same link as in issue #1321): https://www.dropbox.com/scl/fi/tgbmx8b690orvcc31yp7a/RetopoFlow_v4.0.0-alpha-GitHub.zip?rlkey=380tjledg3h3o0c9g3xc1vloo&st=34u2ntfs&dl=0

[JornBoven]

I can confirm that it works on my side too. Thank you for your attention to this issue~ I appreciate it!