Replace printf with rl_helper version

To make a better visual interface, we need to handle printf calls at
rl_helper.
Format state in string before printf it
Format string message before print it at parse_ad_data
Fix some code style issues at cmd_pair
Add support for confirmation pair process

There are cases at pair process that we need to ask user if he really
wants to pair with remote.
That input (Y/N) needs to be done out of ssp_request_callback.
Implement pin_request_callback

This callback is used when remote display PIN code and we need to type
PIN code to bluetooth stack.
rl_helper: implement basic navigation keys
rl_helper: encage cursor to use one line only

It's easier to handle one line for input rather than multiple lines, but if
we want to read more bytes, some precautions are needed.
So we handle something like viewport, which will be bytes showed limited
by terminal columns size (here fixed to 80 chars).
rl_helper: add delete key behavior

When delete key is pressed, everything from right position is shifted to
left.
rl_helper: change feed char to insert behavior

Everytime a printable char is fed, the behavior is to insert it at
position (pos variable). So any chars from right needed to be shifted
one position to right.