Better display/layout for function types in parameters and returns

[that-hatter]

Currently, it requires switching between pages back and forth to read a full function signature, due to function types simply linking to their page, which isn't ideal. Suggestions on how to display them can be presented here. A few things to consider:

1. How they should be displayed in the bulleted list.
2. How they should be displayed in the signature line.
3. Types that are used more than once in one page.
4. Nested types. A function that takes a function that takes a function...

Related:

1. What about on discord? Messages can't have hover popups, and explaining each param of each used function type easily goes over the 2k limit.
2. The specs also support table types. Could the solution here be reused for that?

(more things may be added later)