refactor(nextcloud)!: Remove WebDavFile in favor of low-level WebDavResponse

[provokateurin]

Necessary refactor for #718.
Extension helpers are still there to offload the small part of logic that is useful for consumers (while the rest was just proxy variables).

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 28.71%. Comparing base (548176b) to head (efc8823).

Files with missing lines	Patch %	Lines
.../src/api/webdav/utils/webdav_response_helpers.dart	0.00%	9 Missing ⚠️

Additional details and impacted files

@@                         Coverage Diff                         @@
##           test/nextcloud/all-props-parsed    #2561      +/-   ##
===================================================================
- Coverage                            28.71%   28.71%   -0.01%     
===================================================================
  Files                                  366      366              
  Lines                               136274   136280       +6     
===================================================================
  Hits                                 39128    39128              
- Misses                               97146    97152       +6     

Flag	Coverage Δ		*Carryforward flag
account_repository	98.76% <ø> (ø)
cookie_store	99.48% <ø> (ø)		Carriedforward from 548176b
dashboard_app	96.05% <ø> (ø)
dynamite	31.05% <ø> (ø)		Carriedforward from 548176b
dynamite_end_to_end_test	61.69% <ø> (ø)		Carriedforward from 548176b
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from 548176b
interceptor_http_client	97.18% <ø> (ø)		Carriedforward from 548176b
neon_dashboard	96.05% <ø> (ø)		Carriedforward from 548176b
neon_framework	59.20% <ø> (ø)
neon_http_client	97.50% <ø> (ø)
neon_notifications	100.00% <ø> (ø)		Carriedforward from 548176b
neon_storage	94.66% <ø> (ø)
neon_talk	99.45% <ø> (ø)		Carriedforward from 548176b
nextcloud	24.31% <0.00%> (-0.01%)	⬇️
notifications_app	97.40% <ø> (ø)
notifications_push_repository	98.59% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from 548176b
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
.../src/api/webdav/utils/webdav_response_helpers.dart	0.00% <0.00%> (ø)