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

distro/pkg/deb/control

@@ -22,6 +22,7 @@ Build-Depends:
  meson (>= 0.49),
  protobuf-c-compiler,
  python3-all,
+ python3-dev,
  python3-setuptools,
  libssl-dev,
 Homepage: https://www.knot-resolver.cz/