feat(gateways): Iggy Kafka bridge core (#3533)

[ryerraguntla]

Summary

• Initial Kafka–Iggy bridge core for Kafka gateway: Kafka gateway IggyBridge core — SDK client and stream/topic mapping #3533

Test plan

• cargo test -p iggy-gateway-kafka (or crate name you use)
• CI required checks green

[ryerraguntla]

/author

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.17%. Comparing base (ca0b578) to head (89e1c52).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #4043   +/-   ##
=========================================
  Coverage     85.17%   85.17%           
  Complexity     1402     1402           
=========================================
  Files          1237     1237           
  Lines        181722   181722           
  Branches     148015   148016    +1     
=========================================
+ Hits         154783   154790    +7     
+ Misses        22882    22877    -5     
+ Partials       4057     4055    -2     

Components	Coverage Δ
Rust Core	86.11% <ø> (ø)
Java SDK	67.29% <ø> (ø)
C# SDK	75.46% <ø> (+0.07%)	⬆️
Python SDK	90.06% <ø> (ø)
PHP SDK	85.65% <ø> (ø)
Node SDK	96.22% <ø> (-0.03%)	⬇️
Go SDK	69.35% <ø> (+0.06%)	⬆️
see 5 files with indirect coverage changes

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[hubcio]

please dont include #PR_NUMBER in PR title because it'd look weird after merge, e.g.
feat(gateways): Iggy Kafka bridge core (#3533) (#4043)