Documentation/tool improvements

* Document the Realtime provisioning helper better.
* Include the arguments, assumptions (be it default or deductions from table config) in the output of the tool. For example, if we assume that this is a hybrid table (table-config indicates daily push) then print that out.
* Clarify that the tool is estimating resident memory, not mapped memory. If possible, estimate mapped memory and print that out as well.
* Change offheap allocation for consuming segments to be mmap by default (need to evaluate whether this is a good default for all use cases)

Start with the Realtime provisioning helper and its current output, then inspect how table configuration assumptions and resident-memory estimates are derived. Done means the helper documents its inputs and assumptions, reports resident memory clearly, evaluates mapped-memory output, and resolves the mmap default for consuming segments.

Written by the indexing model from the issue text.