Add compound-literal support.

[davidlehn]

• Support currently delayed.
• Feature can be problematic in some use cases.
• Needs more tests and testing.

[codecov-commenter]

Codecov Report

Merging #535 (c5af420) into main (e297249) will increase coverage by 0.03%.
The diff coverage is 91.83%.

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@@            Coverage Diff             @@
##             main     #535      +/-   ##
==========================================
+ Coverage   93.63%   93.66%   +0.03%     
==========================================
  Files          24       24              
  Lines        2986     3033      +47     
==========================================
+ Hits         2796     2841      +45     
- Misses        190      192       +2     

Files Changed	Coverage Δ
lib/jsonld.js	84.27% <ø> (ø)
lib/fromRdf.js	97.10% <90.00%> (-1.40%)	⬇️
lib/toRdf.js	100.00% <100.00%> (+0.75%)	⬆️