refactor(cookie_store): remove universal_io dependency.

[Leptopoda]

The Cookie does not depend on the dart vm and is therefore also usable on web.
To verify this, I've also enabled unit tests on chrome.

[provokateurin]

So you can use it on web, even though it comes from dart:io?

[Leptopoda]

Yes. Most of dartio can also be used on web.
If you take a look at universal_io you can see that only a few classes are not available.

https://github.com/dint-dev/universal_io/blob/master/lib/src/_exports_in_browser.dart

If you also take a look at the Cookie class (the one relevant to this PR) you'll notice that it is a plain dart class unrelated to any native code.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 26.38%. Comparing base (e7d8dbd) to head (30383c6).
Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2413      +/-   ##
==========================================
- Coverage   26.40%   26.38%   -0.02%     
==========================================
  Files         370      370              
  Lines      136662   136719      +57     
==========================================
- Hits        36086    36075      -11     
- Misses     100576   100644      +68     

Flag	Coverage Δ		*Carryforward flag
account_repository	99.64% <ø> (ø)
cookie_store	99.48% <ø> (-0.52%)	⬇️
dashboard_app	96.05% <ø> (ø)
dynamite	31.08% <ø> (ø)		Carriedforward from c152987
dynamite_end_to_end_test	61.84% <ø> (ø)		Carriedforward from c152987
dynamite_runtime	85.40% <ø> (ø)		Carriedforward from c152987
neon_dashboard	96.05% <ø> (ø)		Carriedforward from c152987
neon_framework	43.56% <ø> (ø)
neon_http_client	93.28% <ø> (ø)
neon_notifications	100.00% <ø> (ø)		Carriedforward from c152987
neon_talk	99.45% <ø> (ø)		Carriedforward from c152987
nextcloud	22.29% <ø> (-0.06%)	⬇️
notifications_app	100.00% <ø> (ø)
sort_box	90.90% <ø> (ø)		Carriedforward from c152987
talk_app	99.09% <ø> (ø)

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

Files	Coverage Δ
...kages/cookie_store/lib/src/cookie_persistence.dart	98.61% <ø> (-1.39%)	⬇️
packages/cookie_store/lib/src/cookie_store.dart	100.00% <ø> (ø)

... and 4 files with indirect coverage changes