Allow rz-find to use the Yara plugin for searching among files

[XVilka]

Currently, rizin has the Yara plugin: https://github.com/rizinorg/rz-libyara
Also, rz-find is able to search among directories and files recursively.

We should allow rz-find to use Yara signatures as well if rz-libyara is installed.

[LukeTheEngineer]

Seems like something nice for the backburner. I'll look into it.

[XVilka]

One way to approach this would be modifying rz-libyara plugin to use the RzIO instead of the RzCore, and RzIO is easily accessible in librz/main/rz-diff.c file.