Ark: Add a direct link to the full help pane from the help-on-hover pop up

[DavisVaughan]

See this discussion https://github.com/posit-dev/positron/discussions/4956

And this feature, where sjmisc::frq in the help-on-hover pop up is clickable to jump to the full help pane

[wch]

I think it would be helpful if there was some indication that clicking on the name of the function would open it in the Help panel. If the text is just a regular-looking link (in the screenshot below, the toJSON, fromJSON {jsonlite}), then it won't be obvious that clicking on it will open it in the Help panel, and the user might think that it'll open in a web browser. Maybe an icon?