fix: ensure scarb compilation even when root package is missing

[glihm]

Scarb can be compiled without having a root package. To ensure compatibility for bindgen and library compilation, bindgen uses now a default NO_ROOT_PACKAGE in case it can't be found.

Closes #1758
Closes DOJ-320

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 67.85%. Comparing base (c595fc9) to head (ac14b42).
Report is 1 commits behind head on main.

Files	Patch %	Lines
crates/dojo-lang/src/scarb_internal/mod.rs	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1759      +/-   ##
==========================================
+ Coverage   67.81%   67.85%   +0.03%     
==========================================
  Files         304      304              
  Lines       33150    33164      +14     
==========================================
+ Hits        22482    22502      +20     
+ Misses      10668    10662       -6     

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