Replace nssm.exe and install the Windows service differently

Issue #1302 (and others in the past) highlight that nssm, an application we use to run `couchdb.cmd` as the service launcher for CouchDB, is sometimes detected as risky software by 3rd party virus detectors. This is because Microsoft Windows doesn't allow registration of batch/command/shell script files as services - only .exes.

We can work around this by writing a standalone exe that replaces `couchdb.cmd`. This can be installed as the service instead.

Alternative solutions may also be possible.

Start by reading the existing couchdb.cmd and how nssm.exe is used to register CouchDB as a Windows service. Done means replacing that launcher and service registration without nssm.exe while avoiding the third-party antivirus detections described in the issue.

Written by the indexing model from the issue text.