Added keybindings for terminal find next and find previous and updated regex, whole word, and case sensitive keybindings to match the way next and previous work. Fixes #29661

Added a try catch around pty spawn to handle case where the file passed into spawn does not exist (#58912)

Fixes #31301

fixes #58327

insert next/prev suggestions

fixes #52787

make tabCompletion be 'on' | 'off' | 'onlySnippets', only compute word end key when tab completion is enabled

add shy-flag that controls when/how the suggest widget shows, improve triggerSuggatAndAcceptBest logic works

fixes #58308