Add SDF::SetRoot and deprecate non-const SDF::Root

[scpeters]

🎉 New feature

Deprecate the setter API that doesn't start with Set

Summary

I just noticed this API that should be called SetRoot. I've updated it here, and I don't see it used in other Garden packages, so I don't think this will introduce deprecation warnings.

Test it

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #1070 (efba699) into main (77478ed) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1070   +/-   ##
=======================================
  Coverage   83.11%   83.11%           
=======================================
  Files         154      154           
  Lines       18682    18685    +3     
=======================================
+ Hits        15527    15530    +3     
  Misses       3155     3155           

Impacted Files	Coverage Δ
src/SDF.cc	94.04% <100.00%> (+0.10%)	⬆️
src/parser.cc	87.17% <100.00%> (ø)

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[ahcorde]

src/SDF_TEST.cc is failing

[ahcorde]

LGTM with green CI