Closes #358 by deleting the 'index' modules which dune creates for us, like Middle.ml
Adds interfaces and documentation for a couple more existing modules, namely Canonicalize and Stan_math_signatures
Removes Frontend_utils by finding better homes for what lived there (basically all of it's functions were only called in one place and not generalizable)
Submission Checklist
[x] Run unit tests
Documentation
[x] OR, no user-facing changes were made
Release notes
Cleaned up the internal structuring of modules in the compiler
This does a few things:
CanonicalizeandStan_math_signaturesFrontend_utilsby finding better homes for what lived there (basically all of it's functions were only called in one place and not generalizable)Submission Checklist
Release notes
Cleaned up the internal structuring of modules in the compiler
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)