One thing I noticed as part of my work on#121 is that our attempted fix introduced in#92 wasn't working as expected if the user had a VPN configuration installed before#86.

This PR fetches the unique name of the VPN service dynamically, as part of the script, such that the service is started and stopped regardless of whether the service is called "Coder" or the older "CoderVPN".

This also ensures we don't break it again if we ever change that name, such as to "Coder Connect" (I don't totally recall why it was set to "Coder", but I don't mind it)