feat: nvswitch telemetry gaps (dsx-ai-factory#2945)

## Description

This PR covers the **NV Switch** port from dsx-ai-factory#2283. It closes the GB200
NVSwitch telemetry gaps for NVUE gNMI streaming, NVUE REST, and NMX-T.

## Type of Change
- [x] **Add** - New feature or capability

## Related Issues
dsx-ai-factory#2283 

## Testing
- [x] Unit tests added/updated
- [x] Manual testing performed

## Additional Notes
Gated previously insecure TLS verification behind
`dangerously_skip_tls_verification` in config surface


- Source mappings were validated against live GB200 NVSwitch endpoints
(gNMI / NVUE-REST / NMX-T).
- **Deployment note:** gNMI TLS verification is now strict by default.
Lab or self-signed
NVOS gNMI endpoints must set `dangerously_skip_tls_verification = true`
to connect.

---------

Signed-off-by: mkoci <[email protected]>

Author: mkoci

crates/health/example/config.example.toml

@@ -212,6 +212,9 @@ logs_state_file = "/tmp/logs_collector_{machine_id}.json"
 [collectors.nmxt]
 scrape_interval = "1m"
 request_timeout = "30s"
+# Keep strict TLS certificate verification by default. Set true only when an
+# NMX-T HTTPS endpoint uses a certificate that cannot be verified normally.
+dangerously_skip_tls_verification = false
 
 [collectors.nvue.rest]
 poll_interval = "1m"
@@ -222,21 +225,32 @@ system_health_enabled = true
 cluster_apps_enabled = true
 sdn_partitions_enabled = true
 interfaces_enabled = true
-
-# NVUE gNMI streaming collector (switches only, disabled by default).
-# Subscribes to gNMI SAMPLE paths and pushes metrics through the DataSink
-# pipeline. PrometheusSink serves the /metrics endpoint; OtlpSink (when
-# configured separately) pushes to an OTel Collector.
+platform_environment_fan_enabled = true
+platform_environment_temperature_enabled = true
+platform_environment_status_enabled = true
+
+# NVUE gNMI streaming collector which subscribes to
+# gNMI SAMPLE paths (components + interfaces, plus platform_general when
+# platform_general_enabled is true) and pushes metrics through the configured
+# sinks. gNMI ON_CHANGE targets system-events
 [collectors.nvue.gnmi]
+# periodic SAMPLE (components, interfaces, and platform_general when
+# platform_general_enabled is true)
 gnmi_port = 9339
 sample_interval = "5m"
 request_timeout = "30s"
-# gNMI ON_CHANGE subscription for system events
+# Keep strict TLS certificate and hostname verification by default. Set true only
+# for lab/self-signed NVOS gNMI endpoints where that dangerous bypass is required.
+dangerously_skip_tls_verification = false
+# streaming ON_CHANGE
 system_events_enabled = true
 
 [collectors.nvue.gnmi.paths]
 components_enabled = true
 interfaces_enabled = true
+# Switch-level memory and disk utilization from `/platform-general/state`
+# (a singleton, not keyed by interface or component name).
+platform_general_enabled = true
 
 # ==============================================================================
 # Processors