[RSDK-12271] Check restart_allowed in agent on Windows

[danielbotros]

Description

RSDK-12271 Check restart_allowed in agent on Windows

• Removes runtime OS check for Windows that prevented checking restart_allowed of restart_status endpoint of viam-server

Testing

• On a windows machine, ran Powershell as administrator
• Cloned agent repo, pulled in branch
• Built agent with go build -o viam-agent.exe ./cmd/viam-agent and created C:/etc/ directory with brand new machine's viam.json
• Ran ./viam-agent.exe
• In app, wrote this config to the machine (I observed the error log "maintenance_allowed key b is not a bool value" but this Slack message seems to suggest that anything that isn't explicitly "true" is interpreted as false, so I think this is fine for testing purposes)

{
  "agent": {
    "advanced_settings": {
      "viam_server_env": {}
    }
  },
  "maintenance": {
    "maintenance_allowed_key": "b",
    "sensor_name": "rdk:component:sensor/sensor1"
  },
  "components": [
    {
      "name": "sensor1",
      "api": "rdk:component:sensor",
      "model": "rdk:builtin:fake",
      "attributes": {}
    }
  ]
}

• I then updated the viam_server_env setting with a random env var/value to trigger a restart, and I observed the log viam-server has NOT allowed a restart; will NOT restart suggesting agent on Windows is checking and respecting restart_allowed

I also tested that by undoinging these changes, restart_allowed was no longer respected and viam-server restarts anyway.

[cheukt]

removing myself