[Issue 4175] [pulsar-function-go] Create integration tests for Go Functions for production-readiness (#6104)

This PR is to provide integration tests that test execution of Go functions that are managed by the Java FunctionManager. This will allow us to test things like behavior during function timeouts, heartbeat failures, and other situations that can only be effectively tested in an integration test. 

Master issue: #4175
Fixes issue: #6204 

### Modifications

We must add Go to the integration testing logic. We must also build the Go dependencies into the test Dockerfile to ensure the Go binaries are available at runtime for the integration tests. 
5 files changed
tree: 2c89a2ff9e72fe55d6f6d0a8b8a5e82272c5f11f
  1. distribution/
  2. docker/
  3. tests/