Add --no-input to hide the input section

[junegunn]

Close #2890
Close #1396

I can't think of many use cases. Maybe for really simple menus?

You can't type in queries in this mode, and the only way to trigger an fzf search is to use search(...) or transform-search(...) action.

# Click header to trigger search
fzf --header '[src] [test]' --no-input --layout reverse \
    --header-border bottom --input-border \
    --bind 'click-header:transform-search:echo ${FZF_CLICK_HEADER_WORD:1:-1}'

Issues

• Any action that changes the query is simply ignored.
• Should we respect the initial query? e.g. fzf --no-input --query a
  • This may give the wrong impression that the "query" is still respected in this mode
  • The same can be done using start event. i.e. fzf --no-input --bind start:search:a