Support for conversion and validating webhooks

[nabokihms]

Is your feature request related to a problem? Please describe. There are two great PRs in the shell-operator, which add the functionality to use hooks as validating webhooks or conversion webhooks for CRDs. https://github.com/flant/shell-operator/pull/223 https://github.com/flant/shell-operator/pull/250 We need to add the support for these kinds of hooks to addon-operator modules.

Additional context:* The most valuable part is switching hooks on and off on enabling or disabling a module (shell-operator is not capable of doing so without restarts).