fix(dynamite): json schema reference resolving

[Leptopoda]

I did not find a better solution yet.
In theory this already allows us to fetch schemas fro other sources like local filesystem or remote servers.
I did not observe any performance penalty.

Towards: #933

[codecov]

Codecov Report

Attention: Patch coverage is 70.37037% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 29.31%. Comparing base (42885c6) to head (a3c55c1).
Report is 13 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1953      +/-   ##
==========================================
+ Coverage   28.97%   29.31%   +0.34%     
==========================================
  Files         245      245              
  Lines       76496    76519      +23     
==========================================
+ Hits        22161    22430     +269     
+ Misses      54335    54089     -246     

Flag	Coverage Δ		*Carryforward flag
dynamite	22.46% <70.37%> (+10.41%)	⬆️
dynamite_end_to_end_test	62.98% <ø> (ø)
dynamite_runtime	82.65% <ø> (ø)		Carriedforward from 42885c6
neon_dashboard	92.56% <ø> (ø)
neon_framework	38.36% <ø> (ø)
neon_talk	97.01% <ø> (ø)
nextcloud	26.52% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from 42885c6

*This pull request uses carry forward flags. Click here to find out more.

Files	Coverage Δ
...namite/dynamite/lib/src/models/openapi/schema.dart	65.85% <81.81%> (+15.85%)	⬆️
...mite/dynamite/lib/src/models/openapi/schema.g.dart	57.61% <62.50%> (+31.60%)	⬆️

... and 9 files with indirect coverage changes

[provokateurin]

Could this have some tests? I see that it is not breaking anything because none of the generated code has changed, but that is no guarantee it won't break in the future.

[Leptopoda]

We already had the e2e tests for this but I added some directly dynamite nevertheless

[provokateurin]

Commit message has a typo and should be fix(dynamite): json schema reference resolving