Use case:
Some components need to perform actions on a series of classes,
for example an events systems needs to load events listeners classes,
a service container needs to load provider classes to built it,
or Zed needs to load health checks.
There are two strategies for that:
- define classes names manually in a configuration array
- discover classes names in a specific folder
This change allows to ease the discover method, returning an array
of fully qualified class names for a specific folder and prefix,
using PSR-4 convention.
Ref T1678.