feat(neon_talk): Enable editing of chat messages

[provokateurin]

Closes #2071

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 31.15%. Comparing base (85c8071) to head (45e423e).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2277      +/-   ##
==========================================
+ Coverage   30.92%   31.15%   +0.22%     
==========================================
  Files         265      265              
  Lines       96710    96773      +63     
==========================================
+ Hits        29907    30145     +238     
+ Misses      66803    66628     -175     

Flag	Coverage Δ		*Carryforward flag
cookie_store	90.51% <ø> (ø)		Carriedforward from 85c8071
dynamite	31.10% <ø> (ø)		Carriedforward from 85c8071
dynamite_end_to_end_test	60.03% <ø> (ø)		Carriedforward from 85c8071
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from 85c8071
neon_dashboard	96.20% <ø> (ø)
neon_framework	45.90% <ø> (ø)
neon_notifications	100.00% <ø> (ø)
neon_talk	98.46% <100.00%> (+0.28%)	⬆️
nextcloud	27.88% <ø> (+0.20%)	⬆️
sort_box	90.90% <ø> (ø)		Carriedforward from 85c8071

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

Files	Coverage Δ
packages/neon/neon_talk/lib/src/blocs/room.dart	98.61% <100.00%> (+0.11%)	⬆️
packages/neon/neon_talk/lib/src/utils/helpers.dart	72.72% <100.00%> (+44.15%)	⬆️
...ckages/neon/neon_talk/lib/src/widgets/message.dart	98.62% <100.00%> (+0.10%)	⬆️
.../neon/neon_talk/lib/src/widgets/message_input.dart	96.47% <100.00%> (+0.68%)	⬆️
...ackages/neon_framework/lib/src/blocs/accounts.dart	0.00% <ø> (ø)
packages/neon_framework/lib/src/testing/mocks.dart	87.50% <ø> (ø)
...ackages/neon_framework/lib/src/widgets/drawer.dart	62.96% <ø> (ø)

... and 2 files with indirect coverage changes

[provokateurin]

Editing messages is only a feature since Talk 19, so the check for the feature needs to be implemented using the capabilities.

[Leptopoda]

changes look good overall :)