Fix UDS path on Windows

[mostafa]

Currently the UDS path is set to /tmp/gatewayd-plugin-cache.sock, which is not accessible in Windows, hence the plugin fails to run and exists abruptly. The current workaround is to set the path to the current directory, so that the UDS file is created relative to GatewayD, for example METRICS_UNIX_DOMAIN_SOCKET=.\gatewayd-plugin-cache.sock. This helps run the plugin, yet it won't remove the UDS file, hence the next run of the plugin will fail. The following fixes should be made to the plugin to work smoothly on Windows:

• Find a suitable path for UDS file (like %temp% or similar)
• Remove UDS file on cleanup
• Provide a separate plugin config file for Windows, like gatewayd_plugin_windows.yaml
• Have gatewayd plugin install pick up the Windows config file (for Windows builds)
• Have gatewayd plugin init generate plugins config file suitable for Windows