docs: improve/add documentation of Lua types

- Added `@inlinedoc` so single use Lua types can be inlined into the
  functions docs. E.g.

  ```lua
  --- @class myopts
  --- @inlinedoc
  ---
  --- Documentation for some field
  --- @field somefield integer

  --- @param opts myOpts
  function foo(opts)
  end
  ```

  Will be rendered as

  ```
  foo(opts)

    Parameters:
      - {opts} (table) Object with the fields:
               - somefield (integer) Documentation
                 for some field
  ```

- Marked many classes with with `@nodoc` or `(private)`.
  We can eventually introduce these when we want to.

runtime/lua/vim/lsp/handlers.lua

@@ -412,6 +412,7 @@ M[ms.textDocument_hover] = M.hover
 ---@param _ nil not used
 ---@param result (table) result of LSP method; a location or a list of locations.
 ---@param ctx (lsp.HandlerContext) table containing the context of the request, including the method
+---@param config? vim.lsp.buf.LocationOpts
 ---(`textDocument/definition` can return `Location` or `Location[]`
 local function location_handler(_, result, ctx, config)
   if result == nil or vim.tbl_isempty(result) then