feat: add join method to Url class

[Meetesh-Saini]

• added support for URL path joining with optional trailing slashes and multiple arguments.

Change Summary

This PR implements a feature based on pydantic/pydantic#9794 to join URL path into the base URL. It uses the join method from the url crate.

Related issue number

fix pydantic/pydantic#9794

Checklist

• Unit tests for the changes exist
• Documentation reflects the changes where applicable
• Pydantic tests pass with this pydantic-core (except for expected changes)
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.24%. Comparing base (ab503cb) to head (e8bd322).
Report is 185 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1378      +/-   ##
==========================================
- Coverage   90.21%   89.24%   -0.97%     
==========================================
  Files         106      112       +6     
  Lines       16339    17834    +1495     
  Branches       36       41       +5     
==========================================
+ Hits        14740    15916    +1176     
- Misses       1592     1898     +306     
- Partials        7       20      +13     

Files with missing lines	Coverage Δ
src/url.rs	98.42% <100.00%> (+0.10%)	⬆️

... and 50 files with indirect coverage changes

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[codspeed-hq]

CodSpeed Performance Report

Merging #1378 will not alter performance

_{Comparing Meetesh-Saini:dev-url-join (e8bd322) with main (f389728)}

Summary

✅ 155 untouched benchmarks

[davidhewitt]

Thanks for the PR! The signature looks fine, though I think the implementation can be simpler.

[davidhewitt]

I think this just needs test cases and then I would be happy to see this merged. Sorry for the long delay 😬

[Meetesh-Saini]

I've added tests and changed the implementation. Now, it only takes one argument instead of multiple.
I noticed that using multiple arguments can be confusing, especially when trailing_slash=False. Keeping it to one argument makes things clearer, similar to how servo-url and urllib.urljoin work.
For example, the user may expect either of the following. I wasn't sure which one to implement.

            a.join("e", "?q=1", "g", trailing_slash=False) 
                    │     │      │                         
                    └──┬──┘      │                         
                       ▼         │                         
              ┌───► "e?q=1"      │                         
              │        │         │                         
    No trailing slash  └────┬────┘                         
                            ▼                              
                           "g"                             
                                                       
                                                                                       
         a.join("e", "?q=1", "g", trailing_slash=False)
                 │     │      │                        
                 └──┬──┘      │                        
                    ▼         │                        
                 "e/?q=1"     │                        
                    │         │                        
                    └────┬────┘                        
                         ▼                             
                       "e/g"