apache: add extra packages + apache user

This adds extra packages for certain modules (basically the ones that
incur further dependencies), support files etc. This is pretty much
follows Alpine's example.

This updates the httpd.conf patch to _not_ uncomment MIMEMagicFile
(because the module isn't loaded by default) and removes that changes
that aren't needed anymore (because of the added module support). The
patch now only changes the default user.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>