add on_click setting for cpu block

[Dieterbe]

I wanted this so I can easily open a terminal with top running when my cpu usage is high.

Note: this is my first time working with rust. I pretty much just copy pasted code from other blocks.
Took me quite a while to figure out i needed to switch from textwidget to buttonwidget, to make the "name" identifier be emitted for the cpu block, such that click events can have the corresponding name and we can link it back to the cpu block.
some basic instructions for new developers could be helpful for people like me, but otherwise great project 👍

[Dieterbe]

PS: I use this to launch top in a termite window.

on_click = "termite -t top -e '/usr/bin/top -o +%CPU'"

works great

[ammgws]

Thanks!

I think eventually things like on_click should be made as general options that can be applied to any block by default.