Drape model map layers onto reality models

[markschlosseratbentley]

This PR adds support to iTwin.js for draping model map layers onto reality data.

A new property titled drapeTarget has been added to ModelMapLayerProps and ModelMapLayerSettings. When this property is specified as ModelMapLayerDrapeTarget.RealityData, the model map layer will be only draped onto all attached reality data. Supported reality data formats include glTF or b3dm. If drapeTarget is not specified in the properties, it will default to ModelMapLayerDrapeTarget.BackgroundMap, which will only drape the model map layer onto the background map.

TODO:

• Performance testing - results look adequate. Consulted with @MarcNeely.
• Run Image Testing - pixel diff should look good (preliminary results look good)
• Add Image Tests test cases.
• Add unit test.
• NextVersion + screenshot
• Fix broken unit test: https://dev.azure.com/bentleycs/iModelTechnologies/_build/results?buildId=3724311&view=logs&j=751a5ea6-e147-5a0b-b7c5-e28ecfcb00e2&t=742556c9-a44d-5542-8a03-cf20a9c5ac3e&l=11638
• Fix broken unit test: https://dev.azure.com/bentleycs/iModelTechnologies/_build/results?buildId=3726877&view=logs&j=751a5ea6-e147-5a0b-b7c5-e28ecfcb00e2&t=742556c9-a44d-5542-8a03-cf20a9c5ac3e&l=11727

TODO (Future PRs):

• Drape onto iModels
• Highlighting / selecting draped models does not work when they are draped on reality data
• Saved view pipes_draped_onto_reality_model_off in geolocated_pipes.bim is not rendering the draping in DPTA (Image Tests). It is rendering in display-test-app locally. Investigating. The other draping saved views work in DPTA (Image Tests). Issue: In DPTA only, draping onto reality data does not work when the model-being-draped is disabled #7818

Here is an example of draping a model from within an iModel (the piping in the air) onto some glTF reality data (the terrain underneath):

Here is an example of the same dataset as above with the model itself disabled, so you only see the draping onto the glTF reality data:

To test locally, you can open display-test-app and:

• open an iModel
• attach a reality model located somewhere near the iModel
• utilize the keyin fdt attach model maplayer reality while an element is selected - the model associated with that element will drape onto the reality model.

[markschlosseratbentley]

For now, we planned to explicitly advertise support for B3DM and glTF (the testcases we have). We believe glTF will be the most common use case.

I would just not mention formats and just refer to draping on reality models. i3dm isn't useful for reality models and cmpt is rare outside of tests.

References to specific formats have been removed.

[mergify]

This pull request is now in conflicts. Could you fix it @markschlosseratbentley? 🙏
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