Material versioning to avoid breaking changes

[Cameron-Micka]

Describe the problem

Graphics Tools is used by a bunch of projects that cannot take breaking changes but would like new features and improved workflows. To adopt this, we need a smarter material upgrade system.

Describe the solution you'd like

One way to achieve this is to build a similar system to what is found in Unity's SRP MaterialPostprocessor.

Describe alternatives you've considered

None at the moment.

Additional context

With a solution like this we can run special logic when a project updates the Graphics Tools package to also update the materials.