SimpleChat: Simple histogram/repeatMatching driven garbageTrimming, Settings UI, Streaming mode, OpenAi Compat (Model, Authorization Bearer), Save/Restore session, Auto Settings UI (#7548)

* SimpleChat:DU:BringIn local helper js modules using importmap

Use it to bring in a simple trim garbage at end logic, which is
used to trim received response.

Also given that importmap assumes esm / standard js modules, so
also global variables arent implicitly available outside the
modules. So add it has a member of document for now

* SimpleChat:DU: Add trim garbage at end in loop helper

* SimpleChat:DU:TrimGarbage if unable try skip char and retry

* SimpleChat:DU: Try trim using histogram based info

TODO: May have to add max number of uniq chars in histogram at
end of learning phase.

* SimpleChat:DU: Switch trim garbage hist based to maxUniq simple

Instead of blindly building histogram for specified substring
length, and then checking if any new char within specified min
garbage length l...