Fix CSI pattern regexp to accept parameter bytes and intermediate bytes

[tompng]

Fix CSI_REGEXP pattern.
Reline::Unicode will handle CSI escape sequence like "\e[1 q" \e[?1234h correctly.
Example inputrc

set show-mode-in-prompt on
set vi-cmd-mode-string "\1\033[1 q\2"
set vi-ins-mode-string "\1\033[5 q\2"

Fixes ruby/irb#1118