manager: build manager and install its files with meson

• build manager and install its files with meson, manager option is disabled by default
• update packaging for manager with meson (not needed, manager build is disabled by default, old packaging is used)
• doc/build.rst (build from source):
  • update information about building knot-resolver with manager
  • add information about building knot-resolver from source with apkg (for supported distros) + instructions for installing apkg

manager/knot_resolver_manager/cli/cli.in

+@cmd@
\ No newline at end of file