Robot Importer: copy texture files

[jhanca-robotecai]

This is a PoC code for copying textures (indicated by #477). I am open to discussions.

Please note, that this PR does not solve the problem of missing mesh (e.g. gltf file might store mesh in a separate binary file).

Test mesh:
texture.zip
Outcome:

[jhanca-robotecai]

Please note, that I also fixed some typos and removed unused code...

[jhanca-robotecai]

TODO: there might be some problems with path resolving if the textures are located in different folder - this will be fixed later if the approach is approved.

[jhanca-robotecai]

TODO: there might be some problems with path resolving if the textures are located in different folder - this will be fixed later if the approach is approved.

Fixed. The code was tested for the following configurations:

texture
├── face.dae
├── face.jpg
└── face.urdf
texture1
├── face.urdf
└── mesh
    ├── face.dae
    └── textures
        └── face.jpg
texture2
├── face.urdf
├── mesh
│   └── face.dae
└── textures
    └── face.jpg

and resulted in the following structure in Assets folder:

├── Importer
│   ├── texture1.prefab
│   ├── texture2.prefab
│   └── texture.prefab
└── UrdfImporter
    ├── 1266655632_face
    │   ├── face.dae
    │   └── face.dae.assetinfo
    ├── 1535885513_face
    │   ├── face.dae
    │   ├── face.dae.assetinfo
    │   └── face.jpg
    ├── 3533555601_face
    │   ├── face.dae
    │   ├── face.dae.assetinfo
    │   └── textures
    │       └── face.jpg
    └── textures
        └── face.jpg

[jhanca-robotecai]

The code does not solve all possible problems with textures (textures might come from another package), but it solves multiple cases existing in robots (e.g. ANYmal C ) and it is a step forward comparing to the previous codebase.

[mbalfour-amzn]

I have a feeling this logic is going to need some iteration over time, but I'm OK with it going in and improving it as we hit issues. Some of the things I'm thinking about:

• If the mesh refers to textures that can't be found, this doesn't look like it's doing much in the way of error-detection and reporting yet.
• @lumberyard-employee-dm We might hit an odd problem with some upcoming work, where we add URI prefix resolution for material textures to the asset import. For the URI prefix resolution to work, it needs to be able to find the texture. If we try to do the resolution before copying the textures, the textures won't exist anywhere that we can find them yet. If we try to copy the textures first, we won't have done the prefix resolution yet to know how to copy them. It's possible we'll need to do it in both places... :(