elisp support

[spcbfr]

Please note: New lexers are contributed to Rouge from the community. Your request will help the community in developing a lexer but it does not mean that anyone will develop the lexer.

The name of the language Emacs-lisp (elisp) here is the syntax

Implementation in other libraries prism supports elisp, not sure if that counts

Additional context A lot of people use elisp for their emacs configuration (me being one of them), and I have my literate config in gitlab since gitlab uses rouge for it's syntax highlighting, I get no syntax highlighting