Implements make_struct

[zslayton]

A follow-on PR will implement make_field.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Attention: Patch coverage is 78.44828% with 25 lines in your changes missing coverage. Please review.

Project coverage is 77.76%. Comparing base (3c76865) to head (3f2cab7).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/lazy/expanded/struct.rs	76.78%	9 Missing and 4 partials ⚠️
src/lazy/struct.rs	0.00%	7 Missing ⚠️
src/lazy/expanded/mod.rs	0.00%	3 Missing ⚠️
src/lazy/expanded/macro_evaluator.rs	97.87%	1 Missing ⚠️
src/lazy/expanded/template.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #876      +/-   ##
==========================================
+ Coverage   77.74%   77.76%   +0.02%     
==========================================
  Files         136      136              
  Lines       34387    34493     +106     
  Branches    34387    34493     +106     
==========================================
+ Hits        26733    26824      +91     
- Misses       5667     5678      +11     
- Partials     1987     1991       +4     

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