* Add simple mode
The current UI is too complicated for some first time users.
This commit adds a "Advanced mode" toggle that defaults on but can be
turned off. When the toggle if switched off, the simple mode is
activated and following UI elements are hided:
- Model parameters setting
- Role switch
- Save button (This means user must save *and* submit in simple mode.)
* Simple mode: Fix ctrl-enter in non-sticky blocks
* i18n
* hide token count
* add back save button
* remove unused variables
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Co-authored-by: Jing Hua <tohjinghua123@gmail.com>
