Added SAI dump support to syncd

[andrii-savka]

No description provided.

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[kcudnik]

What is purpose of this change? there is already saidump tool which dumps redis database to file

[andrii-savka]

To @kcudnik
The purpose of this change is to dump the real SAI state including SDK log.
The "saidump" tool dumps only the sairedis database - not a SAI layer and it could be different.
It is new feature introduced for dumping the SAI and SDK log and add them to sysdump.

[kcudnik]

This could be done easier if you would use connect to existign sai with INIT == false, similar like saidiscovery tool