CI: retain and publish conf_nut_report_feature

[jimklimov]

Help developers using ci_build.sh (including CI builds) quickly look up what NUT features were enabled in a build.

[jimklimov]

In relation to this PR, now extending the NUT configuration reports to clarify where it plans to make a mess for third-party integrations (in #1787 doing this for Python initially), e.g.:

NUT Configuration summary:
==========================

* build serial drivers: no
* build USB drivers:    no
* build neon based XML driver:  no
* enable Avahi support: no
* build Powerman PDU client driver:     no
* build Modbus driver:  no
* build IPMI driver:    no
* build Mac OS X meta-driver:   no
* build i2c based drivers:      no
* enable SSL support:   yes (OpenSSL)
* enable libwrap (tcp-wrappers) support:        yes
* enable libltdl (Libtool dlopen abstraction) support:  yes
* build nut-scanner:    no
* build CGI programs:   no
* install NUT-Monitor desktop application:      no
* install PyNUT binding module: yes
* use default  Python  interpreter:     /usr/bin/python
* use specific Python2 interpreter:
* use specific Python3 interpreter:     /usr/bin/python3.8
* build and install documentation:      man=auto
* build specific documentation format(s):       yes  man
* build and install the development files:      no
* consider basic SMF support:   no
* consider basic systemd support:       yes
* build with tighter systemd support:   yes
* build C++11 codebase (client library, etc.):  yes
* build C++ tests with CPPUNIT: yes
* build SNMP drivers:   no
* build SNMP drivers with statically linked lib(net)snmp:       no
* User to run as:       nobody
* Group of user to run as:      nogroup

NUT Paths:
----------

* Default installation prefix path:     /usr/local/ups
* State file path:      /var/state/ups
* Unprivileged PID file path:   /var/state/ups
* Privileged PID file path:     /run
* Driver program path:  /usr/local/ups/bin
* CGI program path:     /usr/local/ups/cgi-bin
* HTML file path:       /usr/local/ups/html
* Config file path:     /usr/local/ups/etc
* Data file path:       /usr/local/ups/share
* Tool program path:    /usr/local/ups/bin
* System program path:  /usr/local/ups/sbin
* System library path:  /usr/local/ups/lib
* System exec-library path:     /usr/local/ups/libexec

NUT Paths for third-party integrations:
---------------------------------------

* Default  Python  interpreter site-packages:   /usr/local/lib/python3.8/dist-packages
* Specific Python2 interpreter site-packages:
* Specific Python3 interpreter site-packages:   /usr/local/lib/python3.8/dist-packages
* pkg-config *.pc directory:    ${libdir}/pkgconfig
* Service units for systemd:    /lib/systemd/system
* Shutdown hooks for systemd:   /lib/systemd/system-shutdown
* Systemd-tmpfiles configs:     /usr/lib/tmpfiles.d
* Augeas lenses directory:      /usr/share/augeas/lenses/dist
* Udev rules directory: /lib/udev

NUT Build/Target system info:
-----------------------------

* host env spec we run on:      x86_64-pc-linux-gnu
* host env spec we built on:    x86_64-pc-linux-gnu
* host env spec we built for:   x86_64-pc-linux-gnu
* host OS short spec we run on: x86_64-linux-gnu
* host OS short spec we built on:       x86_64-linux-gnu
* host OS short spec we built for:      x86_64-linux-gnu

NUT Compiler settings:
----------------------

* CC            : gcc
* CFLAGS        : -isystem /usr/local/include -g -O2 -Wno-reserved-identifier -Wno-unknown-warning-option -std=gnu99 -Wno-system-headers -Wall -Wextra -Wsign-compare -pedantic -Wno-error
* CXX           : g++
* CXXFLAGS      : -isystem /usr/local/include -g -O2 -Wno-reserved-identifier -Wno-unknown-warning-option -std=gnu++11 -Wno-system-headers -Wall -Wextra -Wno-error
* CPP           : gcc -E
* CPPFLAGS      :