Add generated payload limit validator

[jmaeagle99]

What was changed

Add a build-time generator and a runtime validator to temporal-serviceclient.

• The generator reads the Temporal API descriptors and writes GeneratedPayloadLimitValidator.java. That file holds one method for each message that can hold a payload. Each method reports the size of the payload and memo fields in that message. Hand-written tables in the generator give a class to every such field: blob, memo, blob with a warning only, or no check. The build fails if a field has no class, and also if a class no longer matches a field.
• The validator takes an outbound request. It measures each payload and memo field in the same way as the server. It compares each size against a warning limit and an error limit. It returns the first error and gives the proto path of the field, for example commands[2].schedule_activity_task_command_attributes.input.

No code calls the validator yet. A later change connects it to the gRPC channel.

Why?

Server limits payload and memo sizes and fails executions that have too-large payloads. These changes allow the SDK to find those oversized payloads and, in future change, choose a different behavior such as proactive failing the task retryably.

The Rust core uses a similar design to automatically detect payload changes in the Temporal API proto messages and forces a decision on how those fields are classified.

Checklist

1. How was this tested: Unit tests

2. Any docs updates needed? No