Prior to this change, when EMQX daemon mode failed to start
it's not quite easy for users to understand what went wrong.
All the know is the node did not start in time
and then instructed to boot the node in 'console' mode wishing
for some logs.
However, the node might actuay be running, causing 'console' mode
to fail with a different reason.
With this change, after a filure of daemon mode boot,
we issue a diagnosis.
1. if node can not be found from ps -ef, instruct the user
to find information in erlang.log.N
2. if the node is found running, but not responding to pings
instruct the user to check if the node name is
resolvable and reachable
3. if the node is responding to pings but emqx app is not
running, then it's likely a bug. so the user is advised
to report a github issue.
* feat(emqx_conf): move conf manager for emqx_machine to emqx_conf
* chore(emqx_conf): change emqx:get_config/2 to emqx_conf:get/2
* fix: common test failed
* fix: badmatch by typo wrong key
* fix(emqx_conf): get the wrong core nodes
* fix(emqx_conf): get core node's tnx_id not latest tnx_id
* fix: add ro_transation when copy conf file
* fix: delete debug info
* fix: change ekka_rlog to mria_rlog
* fix: remove cluster_rpc from emqx_machine.
* fix: don't call ekka:start/0 explicitly
* fix: ekka should be start in emqx_machine
prior to this cahnge emqx node shutdown is done by init:stop
which might have undesired stop order of the applications
in this change, emqx_machine_terminator is added to stop apps
in defined order and then terminate the node in infinite loop
