check for namespace shadowing

[tardyp]

protoc enforces that the name space resolution stops when it found a relative name which starts with a package fragment contained by the current package

e.g:
if package is com.foo
The type foo.Bar relative name resolution will never reach root path, it will stop searching at com.foo.Bar

The reasoning for this behavior I think is to avoid to have the resolution working at a certain point of time, and later somebody defines com.foo.Bar, and then your type is suddently pointing to somewhere else.
This is why I called it shadowing.

a test in protox is created in andrewhickman/protox#84

todo:

• test with this package test framework

Fix: andrewhickman/protox#82

[andrewhickman]

Awesome, thanks for the fix. Looks like a couple of tests are failing but the change looks good to me

[codecov]

Codecov Report

Attention: Patch coverage is 65.11628% with 15 lines in your changes missing coverage. Please review.

Project coverage is 76.24%. Comparing base (4a6dd64) to head (293acbb).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
prost-reflect/src/descriptor/build/mod.rs	68.57%	11 Missing ⚠️
prost-reflect/src/descriptor/error.rs	50.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #126      +/-   ##
==========================================
- Coverage   76.59%   76.24%   -0.35%     
==========================================
  Files          31       31              
  Lines        5426     5456      +30     
==========================================
+ Hits         4156     4160       +4     
- Misses       1270     1296      +26     

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[tardyp]

I think the workflow should pass entirely now. For some reason, github auto-approved a few of my attempts, but not the latest one.