[fiirl serializer] Fix for #4791

[tobias1012]

Contributor Checklist

• [x] Did you add Scaladoc to every public function/method?
• [x] Did you add at least one test demonstrating the PR?
• [X] Did you delete any extraneous printlns/debugging code?
• [X] Did you specify the type of improvement?
• [X] Did you add appropriate documentation in docs/src?
• [X] Did you request a desired merge strategy?
• [x] Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Bugfix
• Internal or build-related (includes code refactoring/cleanup)

Desired Merge Strategy

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

Release Notes

Fixed improper path escape on windows platform during firrtl serialization. Note the makefile in svsim is still not windows compatible.

Reviewer Checklist (only modified by reviewer)

• [ ] Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• [ ] Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• [ ] Did you review?
• [ ] Did you check whether all relevant Contributor checkboxes have been checked?
• [ ] Did you do one of the following when ready to merge:
  • [ ] Squash: You/ the contributor Enable auto-merge (squash) and clean up the commit message.
  • [ ] Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

[tobias1012]

Looks like old commit already merged got in this pull request too, not sure how to fix.

[tobias1012]

This PR seems to fix the last issue apart from the makefile, however I am having a bit of trouble compiling on windows with the oss-cad-suite as the verilator runtime seems to have trouble finding paths generated by chisel