Is your feature request related to a problem? Please describe.

Once we can emit multiple diagnostic items by resolving #5295, we'd like to finally converge with standard WGSL's diagnostic severity model (see https://www.w3.org/TR/WGSL/#diagnostics).

Describe the solution you'd like

Support all severity levels the WGSL spec. supports. Namely:

• warning
• error
• info

Describe alternatives you've considered

-

Additional context

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