Looking at https://www.php.net/manual/en/language.basic-syntax.phptags.php
there are just too many variations and I'm not convinced the added
complexity to support all of them would be worth it here.
Thus, support only the case where closing tag "?>" is either omitted
or on a separate line. A workaround for all other cases is to add
the license header manually.
Can always revisit this later.
Adds support for Dockerfiles, Gemfiles, Ruby files, and Groovy files.
Also, in order to fully support Dockerfile and Gemfiles, a new file
extension parser was created to deal with files that do not have an
extension.
