fix(neon_http_client): Make authorization throttling less agressive

[provokateurin]

The detection flagged some responses that were fine (even though I believe nothing should really use the 401 status code except the authentication middleware), which resulted in the app becoming unusable due to the blocking.

I limited it to OCS responses for now as most requests use that format and we can correctly detect invalid credentials 100% of the time through the custom status code 997.
For non-OCS APIs and WebDAV it might be possible as well, but I think they are not so important and we can add them if ever needed.

I know there are those really ugly nested if blocks, but the alternative would be to chain null-aware casts and I don't think that is much better than this.

[codecov]

Codecov Report

Attention: Patch coverage is 78.26087% with 5 lines in your changes missing coverage. Please review.

Project coverage is 28.86%. Comparing base (f4e33f6) to head (e2ca39a).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
...rceptors/authorization_throttling_interceptor.dart	78.26%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2582   +/-   ##
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  Coverage   28.85%   28.86%           
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  Files         370      370           
  Lines      136528   136549   +21     
=======================================
+ Hits        39396    39411   +15     
- Misses      97132    97138    +6     

Flag	Coverage Δ		*Carryforward flag
account_repository	98.47% <ø> (ø)
cookie_store	99.48% <ø> (ø)		Carriedforward from 46a0e52
dashboard_app	96.05% <ø> (ø)
dynamite	31.05% <ø> (ø)		Carriedforward from 46a0e52
dynamite_end_to_end_test	61.69% <ø> (ø)		Carriedforward from 46a0e52
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from 46a0e52
interceptor_http_client	97.18% <ø> (ø)		Carriedforward from 46a0e52
neon_dashboard	96.05% <ø> (ø)		Carriedforward from 46a0e52
neon_framework	61.17% <ø> (ø)
neon_http_client	93.61% <78.26%> (-3.89%)	⬇️
neon_notifications	100.00% <ø> (ø)		Carriedforward from 46a0e52
neon_storage	94.66% <ø> (ø)		Carriedforward from 46a0e52
neon_talk	99.45% <ø> (ø)		Carriedforward from 46a0e52
nextcloud	24.33% <ø> (ø)		Carriedforward from 46a0e52
notifications_app	97.40% <ø> (ø)
notifications_push_repository	98.11% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from 46a0e52
talk_app	98.94% <ø> (ø)

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

Files with missing lines	Coverage Δ
...rceptors/authorization_throttling_interceptor.dart	89.28% <78.26%> (-10.72%)	⬇️

[Leptopoda]

Now we also need tests validating that:

• non json responses are not intercepted
• json responses not matching the pattern are not intercepted