acme: separate flag to disable the 'domains=' array

acme: separate flag to disable the 'domains=' array

PVE has 2 domain lists, PMG only 1 since it requires the
additional type.

In PBS I do not want to have 2 lists either, since it seems
rather inconvenient to have 2 different ways to access the
same list.

Currently we decide this based on whether we have multiple
certificate types, which in PBS we don't, so we need a
separate option for this.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>