perf: replace ObjectNormalizer with json_(en/de)code (de)serializer

[LounisBou]

Redis deserializes every message on every worker before any topic filtering. Deserializations using reflection per each publish can cost a lot.

This PR change it for json_encode/json_decode + constructor mapping over the trivial Update/Message DTOs (should be really cheaper per message).

• Wire format is byte-compatible with the previous ObjectNormalizer output. This should be transparent change for Redis.
• Message.id is keep (not regenerated).
• Existing transport tests pass unchanged, proving equivalence.

[bpolaszek]

Sounds good to me, I even think we can remove symfony/serializer from deps, WDYT?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (babfcd2) to head (edc1b7d).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##                main       #49   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
+ Complexity       165       164    -1     
===========================================
  Files             27        27           
  Lines            437       465   +28     
===========================================
+ Hits             437       465   +28     

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[LounisBou]

Sounds good to me, I even think we can remove symfony/serializer from deps, WDYT?

I choose to keep it as dev dependency so tests prove new format is the same as symfony/serializer

[bpolaszek]

Thank you @LounisBou !