fix: scope generated protobuf classes under SDK namespace to avoid FQCN conflicts

[imshubham22apr-gif]

What does this PR do?

Scopes generated protobuf classes under an SDK-specific namespace to avoid FQCN conflicts when the SDK is used alongside hedera-protobuf-java-api.

Why is this needed?

Some protobuf files define their own java_package (e.g. com.hedera.hapi.*), which can lead to classpath conflicts if both SDK and protobuf artifacts are present in a project.

What is included?

1. Adds a build-level transformation step that remaps java_package values during generation
2. Leaves upstream .proto files unchanged
3. Ensures all generated classes are placed under com.hedera.hashgraph.sdk.proto.*

Notes :-

1. No changes to protobuf source files
2. Minimal, build-only change for safer maintenance
3. Verified with ./gradlew :sdk:assemble

[codacy-production]

Not up to standards ⛔

🔴 Issues 1 medium

Alerts:
⚠ 1 issue (≤ 0 issues of at least minor severity)

Results:
1 new issue

Category	Results
Complexity	1 medium

View in Codacy

🟢 Metrics 0 complexity

Metric	Results
Complexity	0

View in Codacy

_{NEW Get contextual insights on your PRs based on Codacy's metrics, along with PR and Jira context, without leaving GitHub. Enable AI reviewer
TIP This summary will be updated as you push new changes.}