feat(nextcloud): Add support for checksums for uploading WebDAV files

[provokateurin]

Extracted from #2431

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 27.21%. Comparing base (63330c5) to head (4380f5a).
Report is 13 commits behind head on main.

Files with missing lines	Patch %	Lines
...es/nextcloud/lib/src/api/webdav/webdav_client.dart	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2436   +/-   ##
=======================================
  Coverage   27.21%   27.21%           
=======================================
  Files         370      370           
  Lines      136663   136668    +5     
=======================================
+ Hits        37188    37192    +4     
- Misses      99475    99476    +1     

Flag	Coverage Δ		*Carryforward flag
account_repository	99.64% <ø> (ø)
cookie_store	100.00% <ø> (ø)		Carriedforward from 63330c5
dashboard_app	96.05% <ø> (ø)
dynamite	31.08% <ø> (ø)		Carriedforward from 63330c5
dynamite_end_to_end_test	61.84% <ø> (ø)		Carriedforward from 63330c5
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from 63330c5
neon_dashboard	96.05% <ø> (ø)		Carriedforward from 63330c5
neon_framework	43.55% <ø> (ø)
neon_http_client	93.28% <ø> (ø)
neon_notifications	100.00% <ø> (ø)		Carriedforward from 63330c5
neon_talk	99.45% <ø> (ø)		Carriedforward from 63330c5
nextcloud	23.26% <80.00%> (+<0.01%)	⬆️
notifications_app	100.00% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from 63330c5
talk_app	99.09% <ø> (ø)

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

Files with missing lines	Coverage Δ
...es/nextcloud/lib/src/api/webdav/webdav_client.dart	99.34% <80.00%> (-0.66%)	⬇️

[provokateurin]

The WebDavClient parameters (order) and doc comments are quite messy. I'll give it a cleanup after this PR.