Control Recursive Mutations using a flag

With the design being proposed as part of MB-27268 ,  source bucket will be allowed to be mutated from inside the Function. But the resulting mutations in DCP will not be processed by the Function again. 

A flag is being proposed(default value: false/disabled) that allows this behaviour to be controlled by REST API. That is, when the flag is enabled, all resulting mutations will continued to be processed by the same Function(and will not be suppressed).

There is a concern that allowing such behaviour might nuke the server; though the concern is valid, the behaviour is disabled by default and the REST API will allow this behaviour to be configured for those customers who request it.

Assigning this in feature-backlog for now, and will wait for CBSEs to track the asks/priority suitably.