refactor!: `vim.lsp.inlay_hint()` -> `vim.lsp.inlay_hint.enable()`
Problem:
The LSP specification allows inlay hints to include tooltips, clickable
label parts, and code actions; but Neovim provides no API to query for
these.
Solution:
Add minimal viable extension point from which plugins can query for
inlay hints in a range, in order to build functionality on top of.
Possible Next Steps
---
- Add `virt_text_idx` field to `vim.fn.getmousepos()` return value, for
usage in mappings of `<LeftMouse>`, `<C-LeftMouse>`, etc
448907f65d