TestClient methods return Result, not _ResultBase

[CaselIT]

Follow up of #2209 cc @davetapley

Fixes #2207

[CaselIT]

Moved to draft for now, I'll look at the failure next week.

@vytas7 I don't remember if we settled on installing typing_extensions on v4 to better support typing

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (4910dd7) 100.00% compared to head (9cecfe8) 99.94%.

Files	Patch %	Lines
falcon/testing/client.py	96.19%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##            master    #2211      +/-   ##
===========================================
- Coverage   100.00%   99.94%   -0.06%     
===========================================
  Files           62       62              
  Lines         6880     6919      +39     
  Branches      1099     1099              
===========================================
+ Hits          6880     6915      +35     
- Misses           0        4       +4     

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[vytas7]

No, I'd love to keep the "production" installation of Falcon free of any dependencies. Is it possible to instruct the type checker to install these extensions?

Also, it is probably OK to add these dependencies on older Python versions. We don't even ship Linux wheels for some of them.

[CaselIT]

Is it possible to instruct the type checker to install these extensions?

I don't think so.

I'll try doing something more sophisticated wrt import