Add Class[icingaweb2] w/ File[icingaweb2cfgDir]

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icingaweb2::config::general: require File[icingaweb2cfgDir] (from Class[icingaweb2])

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icinga2: Service[icinga2]: require User[icinga]

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icingaweb2_dev: add File[/etc/icingaweb/enabledModules]

refs #6842