Make var peek max string length user configurable

[juslintek]

Hi,

I am debugging services php-fpm processes that hang up to scavenge culprits of why it might have happened, because usually when its stuck nothing is getting out. So when I do:

phpspy -P php-fpm -g globals._POST
phpspy -P php-fpm -g globals._GET
phpspy -P php-fpm -g globals._SERVER
phpspy -P php-fpm -e 'exception@/file_path_to_probable_cause_of_exception:1-endoffile'

if I get any values theyr are printed I thin at max of 255 chars, I might be wrong. But I think there is some limit. Tried to play with -b (buffer) flag, setting it to 99999, didn't help. Any ideas? Doing this on Ubuntu 22.04 and php 8.1.