Add capability to publish metrics to prometheus (NVIDIA#2684)

### Description
One of the feature request is to add system metrics to monitoring FLARE
running metrics via Prometheus + Grafana or other monitoring systems.

This PR add that missing piece.  Here are few pieces to make this work

1) JobMetricsCollector/SysMetricsCollecor, this collector will subscribe
a callback for the ReservedTopic.APP_METRICS topic in the DataBus; and
receive callback when the topic is published.

The SysMetricsCollector listens to the parent process events ( system
start/end etc.) for client and server process
The JobMetricsCollector listens to the job process events, mostly
related to the job, task etc.

2) StatsD-reporter
The statsd-reporter post the the metrics received ( from event callback)
to the statsd-exporter interface: by default localhost:9125.

StatsD-export expose the <host>:9102/metrics web interface for
Prometheus to scrape, which can be used as data source for Grafana to
visualize.
These are standard setup. we added an example with docker-compose file
to illustrate this process

## NVFLARE Monitoring Metrics

| Event | Metric Count | Metric Time Taken |
|-------|--------------|-------------------|
| SYSTEM_START | _system_start_count | |
| SYSTEM_END | _system_end_count | _system_time_taken |
| ABOUT_TO_START_RUN | _about_to_start_run_count | |
| START_RUN | _start_run_count | |
| ABOUT_TO_END_RUN | _about_to_end_run_count | |
| END_RUN | _end_run_count | _run_time_taken |
| CHECK_END_RUN_READINESS | _check_end_run_readiness_count | |
| SWAP_IN | _swap_in_count | |
| SWAP_OUT | _swap_out_count | |
| START_WORKFLOW | _start_workflow_count | |
| END_WORKFLOW | _end_workflow_count | _workflow_time_taken |
| ABORT_TASK | _abort_task_count | |
| FATAL_SYSTEM_ERROR | _fatal_system_error_count | |
| JOB_DEPLOYED | _job_deployed_count | |
| JOB_STARTED | _job_started_count | |
| JOB_COMPLETED | _job_completed_count | _job_time_taken |
| JOB_ABORTED | _job_aborted_count | |
| JOB_CANCELLED | _job_cancelled_count | |
| CLIENT_DISCONNECTED | _client_disconnected_count | |
| CLIENT_RECONNECTED | _client_reconnected_count | |
| BEFORE_PULL_TASK | _before_pull_task_count |  |
| AFTER_PULL_TASK | _after_pull_task_count | _pull_task_time_taken |
| BEFORE_PROCESS_TASK_REQUEST | _before_process_task_request_count | |
| AFTER_PROCESS_TASK_REQUEST | _after_process_task_request_count |
_process_task_request_time_taken |
| BEFORE_PROCESS_SUBMISSION | _before_process_submission_count |  |
| AFTER_PROCESS_SUBMISSION | _after_process_submission_count |
_process_submission_time_taken |
| BEFORE_TASK_DATA_FILTER | _before_task_data_filter_count |  |
| AFTER_TASK_DATA_FILTER | _after_task_data_filter_count |
_data_filter_time_taken |
| BEFORE_TASK_RESULT_FILTER | _before_task_result_filter_count |  |
| AFTER_TASK_RESULT_FILTER | _after_task_result_filter_count |
_result_filter_time_taken |
| BEFORE_TASK_EXECUTION | _before_task_execution_count |  |
| AFTER_TASK_EXECUTION | _after_task_execution_count |
_task_execution_time_taken |
| BEFORE_SEND_TASK_RESULT | _before_send_task_result_count |  |
| AFTER_SEND_TASK_RESULT | _after_send_task_result_count |
_send_task_result_time_taken |
| BEFORE_PROCESS_RESULT_OF_UNKNOWN_TASK |
_before_process_result_of_unknown_task_count | |
| AFTER_PROCESS_RESULT_OF_UNKNOWN_TASK |
_after_process_result_of_unknown_task_count |
_process_result_of_unknown_task_time_taken |
| PRE_RUN_RESULT_AVAILABLE | _pre_run_result_available_count | |
| BEFORE_CHECK_CLIENT_RESOURCES | _before_check_client_resources_count |
|
| AFTER_CHECK_CLIENT_RESOURCES | _after_check_client_resources_count |
_check_client_resources_time_taken |
| SUBMIT_JOB | _submit_job_count | |
| DEPLOY_JOB_TO_SERVER | _deploy_job_to_server_count | |
| DEPLOY_JOB_TO_CLIENT | _deploy_job_to_client_count | |
| BEFORE_CHECK_RESOURCE_MANAGER | _before_check_resource_manager_count |
|
| BEFORE_SEND_ADMIN_COMMAND | _before_send_admin_command_count | |
| BEFORE_CLIENT_REGISTER | _before_client_register_count | |
| AFTER_CLIENT_REGISTER | _after_client_register_count |
client_register_time_taken |
| CLIENT_REGISTER_RECEIVED | _client_register_received_count | |
| CLIENT_REGISTER_PROCESSED | _client_register_processed_count | |
| CLIENT_QUIT | _client_quit_count | |
| SYSTEM_BOOTSTRAP | _system_bootstrap_count | |


These metrics can be separated into Job Metrics and System Metrics.
System Metrics are associated with the Client and Server parent
processes, while Job Metrics are associated with each job.

We support three different setups: 


![setup-1](https://github.com/user-attachments/assets/c031cf99-a997-4d0d-9601-be1e71394bc3)

![setup-2](https://github.com/user-attachments/assets/dd37ac9b-32d3-4c6f-94f1-b2878dda1616)

![setup-3](https://github.com/user-attachments/assets/28182d8c-3672-41e9-9e3a-227c613ccf31)

The detailed examples for setup 1 and 2 are given using hello-pt 


A few sentences describing the changes proposed in this pull request.

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Quick tests passed locally by running `./runtest.sh`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated.

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