www/opengist: Build fixes and improvements

un-break arm64 by installing both esbuild arches

• stop lang/go from fetching newer toolchains during build
• pet port with portfmt & portclippy, fix pkg-plist

run under non-root user by default

• add UID, GID for opengist user
• amend rc script to support user

PR: 285179
Reviewed by: fox
Sponsored by: SkunkWerks, GmbH