[Pmon] Add new daemon "syseepromd" to pmon docker

[keboliu]

- What I did
Introduce a new daemon syseepromd to pmon, which will post syseeprom info to pmon when starting pmon, and will clear those info when stopping pmon, and will keep monitoring the DB in case the info was cleared.

this PR has a dependency on sonic-net/sonic-platform-daemons#25

- How I did it

1. modify make file to add the new daemon syseepromd
2. add code to generate supervisord conf and start.sh for the new daemon

- How to verify it
build an image include this PR to verify the state DB, thes syseeprom info should be there after pmon started, stop pmon and those info should be removed from the state DB.

- Description for the changelog

dockers/docker-platform-monitor/start.sh.j2
/dockers/docker-platform-monitor/docker-pmon.supervisord.conf.j2
rules/docker-platform-monitor.mk
rules/sonic-post-syseeprom.mk

- A picture of a cute animal (not mandatory but encouraged)

[liat-grozovik]

retest please

[qiluo-msft]

As comment

Unblock

[qiluo-msft]

Only one minor comment, otherwise looks good to me.

[jleveque]

@keboliu: The event listener does not take care of the situation Guohan was concerned about. I think you misunderstood his comment. We are not concerned with clearing the syseeprom data from the DB when PMON exits; syseeprom data is static and should not change. However, the concern Guohan raised was that the STATE_DB could get cleared by other services (config reload, swss restart, etc.). We need a way to recognize the STATE_DB was cleared and repopulate the syseeprom info into the DB.

The SwSS restart scenario shouldn't be a problem because we have configured the PMon service as a dependent of SwSS via systemd. Thus, if SwSS gets restarted, so too should PMon get restarted. However, we still need a way to get notified that the STATE_DB was cleared so we can repopulate the info.

[keboliu]

@keboliu: The event listener does not take care of the situation Guohan was concerned about. I think you misunderstood his comment. We are not concerned with clearing the syseeprom data from the DB when PMON exits; syseeprom data is static and should not change. However, the concern Guohan raised was that the STATE_DB could get cleared by other services (config reload, swss restart, etc.). We need a way to recognize the STATE_DB was cleared and repopulate the syseeprom info into the DB.

The SwSS restart scenario shouldn't be a problem because we have configured the PMon service as a dependent of SwSS via systemd. Thus, if SwSS gets restarted, so too should PMon get restarted. However, we still need a way to get notified that the STATE_DB was cleared so we can repopulate the info.

@jleveque I get the point. Given the demand for repopulating syseeprom info to state DB in any case if it was cleared, what's your view to change the one-shot scripts to a new daemon for populate syseeprom and monitor it?

[jleveque]

@lguohan: Will there ever be an instance where STATE_DB will get cleared which will not be accompanied by a SwSS restart? If so, I agree with @keboliu that we will most likely need a daemon to monitor the DB.

[jleveque]

Approved. However, do not merge until submodule update has been included in this PR.

[jleveque]

@keboliu: sonic-net/sonic-platform-daemons#25 has been merged. Please update the submodule in this PR.

[keboliu]

retest vs please

[keboliu]

@jleveque submodule has been updated, ready for merge:)