foris: refactor foris packages to be really python packages

Compilation was tested and Foris executables now have correct hashbangs.

This uses correct python install sections instead of replacing it with its own. The problem was that python-package.mk does a lot of "standard" fixes in that install and replacing it caused those fixes to be skipped. There might have been originally reason on why to not use default install but I don't see it now.

This also cleans a lot of other stuff around. Because we now use python-package.mk provided install we use Py3Package install instead. The same paradigm is used for optional ForisControllerModule install section.

This also drops unnecessary hash-bang at the beginning of all scripts. Those scripts are not run directly but instead sourced. It is bad practice to do so because those scripts do not include functions they might use (such as config_load and so on). Also note that in default script is interpreted as shell so it is all right even if it is run directly. This is just more cleaner solution.

This also drops all trace sets from same scripts. Most of those were only calling service restart and that is pretty much useless to print trace for that. There is only one exception and that is postinst of controller-netboot-module. It is also doing UCI manipulation. This is invalid in its core because it disallows configuration to be used. I am going to move that change to separate oneshot package used to migrate that configuration in future. That means that those trace outputs should not be required anywhere.

Fixes: https://gitlab.labs.nic.cz/turris/turris-os-packages/issues/404