fix(talk_app): Fix text overflow in message preview with rich object

[provokateurin]

WidgetSpan+Text lead to weird results when there was a rich object that was hidden due to overflow. Just using a TextSpan directly is more performant and correctly handles the overflow.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 30.27%. Comparing base (801599c) to head (2abdd80).
Report is 12 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2497      +/-   ##
==========================================
- Coverage   30.29%   30.27%   -0.03%     
==========================================
  Files         352      352              
  Lines      124389   124321      -68     
==========================================
- Hits        37680    37632      -48     
+ Misses      86709    86689      -20     

Flag	Coverage Δ		*Carryforward flag
account_repository	98.77% <ø> (ø)
cookie_store	99.48% <ø> (ø)		Carriedforward from 801599c
dashboard_app	96.05% <ø> (ø)
dynamite	31.08% <ø> (ø)		Carriedforward from 801599c
dynamite_end_to_end_test	61.69% <ø> (ø)		Carriedforward from 801599c
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from 801599c
neon_dashboard	96.05% <ø> (ø)		Carriedforward from 801599c
neon_framework	57.07% <ø> (-0.03%)	⬇️
neon_http_client	96.69% <ø> (ø)		Carriedforward from 801599c
neon_notifications	100.00% <ø> (ø)		Carriedforward from 801599c
neon_talk	99.45% <ø> (ø)		Carriedforward from 801599c
nextcloud	25.88% <ø> (-0.03%)	⬇️	Carriedforward from 801599c
notifications_app	100.00% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from 801599c
talk_app	99.09% <100.00%> (-0.01%)	⬇️

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

Files with missing lines	Coverage Δ
...ork/packages/talk_app/lib/src/widgets/message.dart	98.99% <100.00%> (-0.01%)	⬇️

... and 1 file with indirect coverage changes