feat: NAPALM drivers for VMware ESXi and vCenter

Two drivers from one package, both in the hypervisor role:

- vmware_esxi talks to one host directly: facts, vmnics and vmkernel
  NICs, CDP/LLDP neighbours, sensors, VMs, datastores and port groups.
- vmware_vcenter talks to a vCenter: every VM of every host it manages,
  with the host as the VM's node, plus distributed port groups. It
  reports no interfaces of its own; the hosts' NICs belong to the hosts.

Both implement the HypervisorDriver VM contract: get_vms, get_vm_config,
start/stop/reboot/suspend_vm and the four snapshot methods, and emit raw
device warnings (maintenance mode, disconnected host, config issues,
host managed by a vCenter, free license making the API read-only).

Every read is a PropertyCollector query for the explicit paths in
paths.py, converted by to_plain() into dicts and lists; the parsers
only ever see that. tools/harvest.py dumps exactly those paths to JSON
and tools/sanitize.py scrubs the dump, so a real host can become a test
fixture without code changes. A VM's vmid is its instance UUID, which
survives vMotion and re-registration; a MoRef does not.

Tested against govmomi's vcsim in ESXi and vCenter mode, including real
power and snapshot tasks. Not yet tested against real hardware.

napalm_vmware/parse/environment.py

@@ -0,0 +1,65 @@
+"""NAPALM ``get_environment`` from host quick stats and hardware sensors."""
+
+from __future__ import annotations
+
+from typing import Any
+
+_SENSORS = "runtime.healthSystemRuntime.systemHealthInfo.numericSensorInfo"
+_MB = 1024 * 1024
+
+
+def _reading(sensor: dict[str, Any]) -> float:
+    return float(sensor.get("currentReading", 0)) * 10 ** int(sensor.get("unitModifier", 0))
+
+
+def _health(sensor: dict[str, Any]) -> str:
+    return (sensor.get("healthState") or {}).get("key", "unknown")
+
+
+def _cpu_percent(host: dict[str, Any]) -> float:
+    hardware = host.get("summary.hardware") or {}
+    capacity = int(hardware.get("cpuMhz") or 0) * int(hardware.get("numCpuCores") or 0)
+    used = (host.get("summary.quickStats") or {}).get("overallCpuUsage") or 0
+    return round(used / capacity * 100, 2) if capacity else 0.0
+
+
+def _add_sensors(env: dict[str, Any], host: dict[str, Any], prefix: str) -> None:
+    for sensor in host.get(_SENSORS) or []:
+        name = f"{prefix}{sensor.get('name', '')}"
+        kind = sensor.get("sensorType")
+        health = _health(sensor)
+        if kind == "temperature":
+            env["temperature"][name] = {
+                "temperature": _reading(sensor),
+                "is_alert": health in ("yellow", "red"),
+                "is_critical": health == "red",
+            }
+        elif kind == "fan":
+            env["fans"][name] = {"status": health == "green"}
+        elif kind == "power":
+            env["power"][name] = {
+                "status": health == "green",
+                "capacity": -1.0,
+                "output": _reading(sensor),
+            }
+
+
+def environment(hosts: list[dict[str, Any]]) -> dict[str, Any]:
+    """One host: keyed like a single device. Several (vCenter): keyed by host."""
+    env: dict[str, Any] = {
+        "fans": {},
+        "temperature": {},
+        "power": {},
+        "cpu": {},
+        "memory": {"available_ram": 0, "used_ram": 0},
+    }
+    single = len(hosts) == 1
+    for host in hosts:
+        key = "0" if single else host.get("name", host["_moref"])
+        env["cpu"][key] = {"%usage": _cpu_percent(host)}
+        hardware = host.get("summary.hardware") or {}
+        stats = host.get("summary.quickStats") or {}
+        env["memory"]["available_ram"] += int(hardware.get("memorySize") or 0)
+        env["memory"]["used_ram"] += int(stats.get("overallMemoryUsage") or 0) * _MB
+        _add_sensors(env, host, "" if single else f"{key}/")
+    return env