feat(neon_talk): Add helpers for parsing timestamps

[provokateurin]

No description provided.

[Leptopoda]

I'm not sure if this should be in the nextcloud package.
Is there anything against having it in neon_talk?

[provokateurin]

Not really, but the helpers can be useful for other people as well, so I don't see why they shouldn't be in the nextcloud package.

[codecov]

Codecov Report

Attention: Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.

Project coverage is 30.92%. Comparing base (c624c39) to head (4c6fe24).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2287      +/-   ##
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- Coverage   30.92%   30.92%   -0.01%     
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  Files         265      265              
  Lines       96709    96710       +1     
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- Hits        29911    29907       -4     
- Misses      66798    66803       +5     

Flag	Coverage Δ		*Carryforward flag
cookie_store	90.51% <ø> (ø)		Carriedforward from c624c39
dynamite	31.10% <ø> (ø)		Carriedforward from c624c39
dynamite_end_to_end_test	60.03% <ø> (ø)		Carriedforward from c624c39
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from c624c39
neon_dashboard	96.20% <ø> (ø)		Carriedforward from c624c39
neon_framework	45.90% <ø> (ø)		Carriedforward from c624c39
neon_notifications	100.00% <ø> (ø)		Carriedforward from c624c39
neon_talk	98.18% <44.44%> (-0.48%)	⬇️
nextcloud	27.67% <ø> (ø)		Carriedforward from c624c39
sort_box	90.90% <ø> (ø)		Carriedforward from c624c39

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Files	Coverage Δ
packages/neon/neon_talk/lib/src/pages/room.dart	100.00% <100.00%> (ø)
...ckages/neon/neon_talk/lib/src/widgets/message.dart	98.51% <100.00%> (-0.03%)	⬇️
packages/neon/neon_talk/lib/src/utils/helpers.dart	28.57% <16.66%> (-71.43%)	⬇️

[Leptopoda]

I'd rather not have them in the nextcloud package, as these fields offer a quite different experience to the rest of the BuiltValue models.

These extensions are not cached, so multiple requests will lead to parsing the time multiple times.
It might also be confusing that to change the time one has to change the string representation.
Yes a quick look at the code will make that clear but I only see a point of cocnfusion.