Stanc.Std: Move drivers over

[WardBrian]

Submission Checklist

• Run unit tests
• Documentation
  • If a user-facing facing change was made, the documentation PR is here:
  • OR, no user-facing changes were made

Release notes

Replace this text with a short note on what will change if this pull request is merged. This will be included in the release notes.

Copyright and Licensing

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the BSD 3-clause license (https://opensource.org/licenses/BSD-3-Clause)

---

_{Stack created with GitHub Stacks CLI • Give Feedback 💬}

[codecov]

Codecov Report

❌ Patch coverage is 79.01235% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.16%. Comparing base (cd739f7) to head (fd7702d).

Files with missing lines	Patch %	Lines
src/std/std.ml	54.16%	11 Missing ⚠️
...analysis_and_optimization/Debug_data_generation.ml	86.66%	4 Missing ⚠️
src/std/Return.ml	66.66%	2 Missing ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##           std/signatures    #1658      +/-   ##
==================================================
- Coverage           92.27%   92.16%   -0.11%     
==================================================
  Files                  68       69       +1     
  Lines                9991    10020      +29     
==================================================
+ Hits                 9219     9235      +16     
- Misses                772      785      +13     

Files with missing lines	Coverage Δ
src/analysis_and_optimization/Mir_utils.ml	78.01% <100.00%> (+0.15%)	⬆️
src/driver/Entry.ml	96.15% <100.00%> (-0.05%)	⬇️
src/driver/Flags.ml	100.00% <ø> (ø)
src/frontend/Errors.ml	100.00% <100.00%> (ø)
src/frontend/Preprocessor.ml	98.75% <100.00%> (ø)
src/stanc/CLI.ml	100.00% <100.00%> (ø)
src/stanc/stanc.ml	87.09% <100.00%> (-0.21%)	⬇️
src/std/Return.ml	66.66% <66.66%> (ø)
...analysis_and_optimization/Debug_data_generation.ml	81.63% <86.66%> (+0.33%)	⬆️
src/std/std.ml	61.53% <54.16%> (-11.80%)	⬇️

... and 1 file with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.