Fix ProtoBuf conversions for Verification IR

[debs-sifive]

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you update the FIRRTL spec to include every new feature/behavior?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you state the API impact?
• Did you specify the code generation impact?
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• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• bug fix

API Impact

None

Backend Code Generation Impact

This should allow Verilog to be generated for Verification IR.

Desired Merge Strategy

• Squash: The PR will be squashed and merged (choose this if you have no preference.

Release Notes

Fixes ProtoBuf conversions for Verification IR.

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels?
• Did you mark the proper milestone (1.2.x, 1.3.0, 1.4.0) ?
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[ekiwi]

This reminds me that the name of print, stop and verification statements might also not be properly serialized to protobuf.

[debs-sifive]

This reminds me that the name of print, stop and verification statements might also not be properly serialized to protobuf.

I'm not sure I understand; it doesn't look like these have name fields?

[ekiwi]

I'm not sure I understand; it doesn't look like these have name fields?

They do now: #2057

And I don't think I actually added them to the protobuf code..