Move prismjs, mermaid, katex, clipboard, and emoji-toolkit to optional peerDependencies #621
Description
Currently, prismjs, mermaid, katex, clipboard, and emoji-toolkit are listed under optionalDependencies, which are installed by default leading to issues like #573
Instead, it would be better to list them under peerDependencies and use peerDependenciesMeta to mark them as optional. That way, consumers can choose if they want to install those libraries or not.