Support for phong shading and lambert material

## What problem does this solve or what need does it fill?

Allow plugin authors to properly implement scene loaders for formats such as Autodesk's FBX or Pixar's USD. Other engines such as Unreal or Unity implements both for comformant asset support.

Of course each plugin can implement their own support but then we get collision if user will try to use both formats handled by different plugins in the same game.

## What solution would you like?

Implement both, phong shading and lambert material.

## What alternative(s) have you considered?

Not supporting both, but then each game or plugin which requires either phong or lambert, will have to fiddle around with custom implementation or just add another layer of PBR material directly from Bevy which definitely is not efficient nor perfomant method.

## Additional context

As we talked with `@robswain#0382` on discord, he said that it's good idea to have support in bevy directly. (see "bevy_fbx development" thread in `#general` on bevy discord)

The issue names no files, tests, or entry points. Start by reviewing how Bevy represents materials and how plugin scene loaders provide them, then compare the needs of FBX and USD workflows. Done means plugin authors can use built-in Phong shading and Lambert materials without custom implementations or collisions between formats.

Written by the indexing model from the issue text.