[garden] Added <shininess> to <material>

[WilliamLewww]

➡️ Forward port #985

Forward port of #985

Note to maintainers: Remember to Merge with commit (not squash-merge or rebase)

[codecov]

Codecov Report

Merging #1018 (68d169c) into main (324a755) will not change coverage.
The diff coverage is n/a.

❗ Current head 68d169c differs from pull request most recent head 7446d8c. Consider uploading reports for the commit 7446d8c to get more accurate results

@@           Coverage Diff           @@
##             main    #1018   +/-   ##
=======================================
  Coverage   66.66%   66.66%           
=======================================
  Files           2        2           
  Lines          27       27           
=======================================
  Hits           18       18           
  Misses          9        9           

Impacted Files	Coverage Δ
src/EmbeddedSdf.cc	100.00% <0.00%> (ø)

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[scpeters]

I believe this was already merged forward in #1024