resolves: https://github.com/elastic/kibana/issues/80120
Adds a new Kibana configuration key xpack.actions.customHostSettings which
allows per-host configuration of connection settings for https and smtp for
alerting actions. Initially this is just for TLS settings, expandable to other
settings in the future.
The purpose of these is to allow customers to provide server certificates for
servers accessed by actions, whose certificate authority is not available
publicly. Alternatively, a per-server rejectUnauthorized: false configuration
may be used to bypass the verification step for specific servers, but require it
for other servers that do not have per-host customization.
Support was also added to allow per-host customization of ignoreTLS and
requireTLS flags for use with the email action.