Review upper/lower class and file matching over code

[stronk7]

While writing the v3.4.3 release notes, it has been noticed that there is some inconsistency with sniffs using the DocBlock (vs Docblock) "word" as part of their names.

This is specially dangerous (I imagine) if there is also a mismatch between the file and the class names in filesystems being case-sensitive.

This issue is about review that exact case and if, maybe, we can add some check to our CI pipeline in order to detect any future mismatch between files and classes.

Ciao :-)