Emacs syntax highlighting for new keywords introduced in parameterised libraries support

[Sudha247]

Syntax highlighting needs to be added in the emacs configuration here: https://github.com/ocaml/dune/blob/main/editor-integration/emacs/dune.el. Documentation about the new keywords can be found here: #12111. This should be a matter of updating the emacs config to include keywords like parameters, library_parameter, etc.