refactor: update BlocObserver instances to use const constructors

[ValentinVignal]

Status

READY

Breaking Changes

NO

Description

Follows #3704 and relates to #3703

This PR updates all the bloc observers to have and use a const constructor.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[ValentinVignal]

@felangel I named the PR refactor(bloc) but I'm not modifying the bloc package. I'm modifying bloc_test flutter_bloc, replay_bloc and several examples.
What title should I give to the PR?

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (0458045) compared to base (c4500b6).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##            master     #3713    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           30        15    -15     
  Lines          709       328   -381     
==========================================
- Hits           709       328   -381     

Impacted Files	Coverage Δ
packages/bloc_test/lib/src/bloc_test.dart	100.00% <100.00%> (ø)
...ackages/hydrated_bloc/lib/src/hydrated_cipher.dart
...ckages/hydrated_bloc/lib/src/hydrated_storage.dart
packages/bloc_concurrency/lib/src/restartable.dart
packages/bloc/lib/src/bloc.dart
packages/bloc_concurrency/lib/src/droppable.dart
packages/bloc_concurrency/lib/src/sequential.dart
packages/bloc/lib/src/cubit.dart
packages/bloc/lib/src/emitter.dart
packages/bloc/lib/src/bloc_base.dart
... and 6 more

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[ValentinVignal]

Thank you for the updates @felangel ! Do you need me to do anything else on this PR?

[felangel]

Thank you for the updates @felangel ! Do you need me to do anything else on this PR?

Thank you! No, I think we’re all set — I’ll get this merged later today 👍