Move Protobuf serde to separate module

[slinkydeveloper]

Fix #249

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Test Results

 92 files  ±0   92 suites  ±0   4m 32s :stopwatch: +8s  79 tests +1   56 :white_check_mark: +1  23 :zzz: ±0  0 :x: ±0  205 runs  +2  143 :white_check_mark: +2  62 :zzz: ±0  0 :x: ±0 

Results for commit a76fb7be. ± Comparison against base commit aee2f719.

This pull request removes 1 and adds 2 tests. Note that renamed tests count towards both.

``` dev.restate.e2e.runtime.IngressServiceTest ‑ idempotentInvoke(IngressClient) ``` ``` dev.restate.e2e.runtime.IngressTest ‑ headersPassThrough(IngressClient) dev.restate.e2e.runtime.IngressTest ‑ idempotentInvoke(IngressClient) ```

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Unit Test Results

  44 files  ±0    44 suites  ±0   1m 43s :stopwatch: +4s 623 tests ±0  594 :heavy_check_mark: ±0  29 :zzz: ±0  0 :x: ±0  624 runs  +1  595 :heavy_check_mark: +1  29 :zzz: ±0  0 :x: ±0 

Results for commit a76fb7be. ± Comparison against base commit aee2f719.