Adds file handlers for the C++ import operators.
This will allow these operators to be invoked with drag-and-drop
filepath data in the 3D Viewport or the Outliner.
When the operators are called with drag-and-drop data a dialog popup
will be used instead of invoking the file select window.
Previously OPTYPE_REGISTER tag had no effect, now since these operators
can run as popup dialogs this flag is removed to prevent heavy io
operations in the redo panel.
Also includes drawing functions for ply and stl and a missing
event notifications to collada import.
Important: Presets can override file path properties, so if a preset is
used, file paths provided by drag and drop will be lost. This will be
addressed in follow up changes.
Pull Request: https://projects.blender.org/blender/blender/pulls/116873
Listing the "Blender Foundation" as copyright holder implied the Blender
Foundation holds copyright to files which may include work from many
developers.
While keeping copyright on headers makes sense for isolated libraries,
Blender's own code may be refactored or moved between files in a way
that makes the per file copyright holders less meaningful.
Copyright references to the "Blender Foundation" have been replaced with
"Blender Authors", with the exception of `./extern/` since these this
contains libraries which are more isolated, any changed to license
headers there can be handled on a case-by-case basis.
Some directories in `./intern/` have also been excluded:
- `./intern/cycles/` it's own `AUTHORS` file is planned.
- `./intern/opensubdiv/`.
An "AUTHORS" file has been added, using the chromium projects authors
file as a template.
Design task: #110784
Ref !110783.
