Use thiserror in re_renderer everywhere except shader file reloading

[Wumpf]

What

• part of Replace anyhow with thiserror in libraries #1845

Started also removing it the file resolver/reloader but it's super tedious and makes errors worse since during include resolve we often want to stack errors. We can revisit that if we ever move out the shader reloading or when we tackle

• Evaluate use of naga_oil instead of custom import handling #2664

but otherwise I don't think it's worth it.

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