Enable forward ssh-port to host

Provides an option to disable the forwarding in case it causes issues.
However based on original PRs adding the forwarded behaviour, it does
not appear to be intentional to exclude it permanently.

Closes: #1011
Closes: #1012

lib/vagrant-libvirt/action/forward_ports.rb

@@ -71,7 +71,7 @@ module VagrantPlugins
               next
             end
 
-            next unless type == :forwarded_port && options[:id] != 'ssh'
+            next if type != :forwarded_port || ( options[:id] == 'ssh' && !env[:machine].provider_config.forward_ssh_port )
             if options.fetch(:host_ip, '').to_s.strip.empty?
               options.delete(:host_ip)
             end

lib/vagrant-libvirt/config.rb

@@ -39,6 +39,9 @@ module VagrantPlugins
 
       attr_accessor :proxy_command
 
+      # Forward port with id 'ssh'
+      attr_accessor :forward_ssh_port
+
       # Libvirt storage pool name, where box image and instance snapshots will
       # be stored.
       attr_accessor :storage_pool_name
@@ -196,6 +199,7 @@ module VagrantPlugins
         @id_ssh_key_file   = UNSET_VALUE
         @socket            = UNSET_VALUE
         @proxy_command     = UNSET_VALUE
+        @forward_ssh_port  = UNSET_VALUE # forward port with id 'ssh'
         @storage_pool_name = UNSET_VALUE
         @snapshot_pool_name = UNSET_VALUE
         @random_hostname   = UNSET_VALUE
@@ -784,6 +788,9 @@ module VagrantPlugins
         finalize_from_uri
         finalize_proxy_command
 
+        # forward port with id 'ssh'
+        @forward_ssh_port = true if @forward_ssh_port == UNSET_VALUE
+
         @storage_pool_name = 'default' if @storage_pool_name == UNSET_VALUE
         @snapshot_pool_name = @storage_pool_name if @snapshot_pool_name == UNSET_VALUE
         @storage_pool_path = nil if @storage_pool_path == UNSET_VALUE