Add NUT plugin

The *collectd-nut* package pulls in *nut-client*, which in turn pulls in
Python (for PyNUT).  Since collectd only needs `libupsclient.so.6`, we
can extact it from the *nut-client* package and install it manually,
avoiding the dependency explosion.

Containerfile

@@ -1,5 +1,11 @@
 FROM registry.fedoraproject.org/fedora:38 AS build
 
+RUN --mount=type=cache,target=/var/cache \
+	dnf install -y \
+		--setopt=install_weak_deps=0 \
+		cpio \
+	&& :
+
 RUN --mount=type=cache,target=/var/cache \
 	dnf install -y \
 		--downloadonly \
@@ -8,6 +14,7 @@ RUN --mount=type=cache,target=/var/cache \
 		collectd \
 		collectd-chrony \
 		collectd-disk \
+		collectd-nut \
 		collectd-sensors \
 		collectd-write_prometheus \
 	&& :
@@ -19,6 +26,9 @@ RUN --mount=type=cache,target=/var/cache \
 		/var/cache/rpms/libmicrohttpd-*.rpm \
 		/var/cache/rpms/libmnl-*.rpm \
 		/var/cache/rpms/protobuf-c-*.rpm \
+	&& cd /sysroot \
+	&& rpm2cpio /var/cache/rpms/nut-client-*.rpm \
+		| cpio -i './usr/lib*/libupsclient.so.6*' \
 	&& :