mgr/dashboard: Add separate option to config SSL port

mgr/dashboard: Add separate option to config SSL port

There is a need to introduce this new config option because the MgrModule::get_module_option() and MgrModule::get_localized_module_option() method will be refactored soon and will not support the default parameter anymore. Instead the default value must be configured in the MODULE_OPTIONS. Currently we misuse the server_port depending on if SSL is enabled or not.

Fixes: https://tracker.ceph.com/issues/38331
Signed-off-by: Volker Theile <vtheile@suse.com>