Move Protobuf serde to separate module

[slinkydeveloper]

Fix #249

[github-actions]

Test Results

 92 files  ±0   92 suites  ±0   4m 32s ⏱️ +8s
 79 tests +1   56 ✅ +1  23 💤 ±0  0 ❌ ±0 
205 runs  +2  143 ✅ +2  62 💤 ±0  0 ❌ ±0 

Results for commit a76fb7b. ± Comparison against base commit aee2f71.

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)

[github-actions]

Unit Test Results

  44 files  ±0    44 suites  ±0   1m 43s ⏱️ +4s
623 tests ±0  594 ✔️ ±0  29 💤 ±0  0 ❌ ±0 
624 runs  +1  595 ✔️ +1  29 💤 ±0  0 ❌ ±0 

Results for commit a76fb7b. ± Comparison against base commit aee2f71.