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

ci/images/manager/Dockerfile

@@ -13,6 +13,6 @@ RUN dnf install -y git diffutils python3.6 python3.7 python3.8 python3.9 python3
 
 # Install Poetry
 RUN python3 -m pip install -U pip \
-	&& curl -sSL https://install.python-poetry.org | python3 - \
+	&& curl -sSL https://install.python-poetry.org | python3 - --version 1.2.2\
 	# not exactly required, but helpful
 	&& python3 -m pip install poethepoet