bors d438c80c45 Auto merge of #13603 - epage:toml3, r=weihanglo
refactor(toml): Expose surce/spans for VirtualManifests

### What does this PR try to resolve?

This is a follow up to #13593, expanding support from `Manifest` to `VirtualManifest` as well.

This also does other clean up along the way in preparation for making a more explicit `resolve_toml` phase.

### How should we test and review this PR?

### Additional information
2024-03-19 16:11:22 +00:00
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