feat!: add optional builder feature limited to Input

[ifiokjr]

Closes #7

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 71.79%. Comparing base (542278f) to head (8fd9e52).
Report is 2 commits behind head on main.

Files	Patch %	Lines
crates/edgedb_codegen_core/src/utils.rs	76.19%	0 Missing and 5 partials ⚠️
crates/edgedb_codegen/src/lib.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #10      +/-   ##
==========================================
+ Coverage   69.62%   71.79%   +2.17%     
==========================================
  Files           6        6              
  Lines         553      578      +25     
  Branches      553      578      +25     
==========================================
+ Hits          385      415      +30     
+ Misses        133      120      -13     
- Partials       35       43       +8     

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