docs(lsp): format arguments to start_client()

Small, but I was getting warnings about my usage of
`vim.lsp.buf_notify(bufnr, method, {example = example})` since the docs
say that `params` must be a string, however this can really be anything
when it's passed to `rpc.notify` since we just end up calling
`vim.json.encode(payload)` on it. This fixes the docs in those two
places and regenerates them.

Fixes https://github.com/neovim/neovim/issues/21523

1. The algorithm for applying edits was slightly incorrect. It needs to
   preserve the original token list as the edits are applied instead of
   mutating it as it iterates. From the spec:

   Semantic token edits behave conceptually like text edits on
   documents: if an edit description consists of n edits all n edits are
   based on the same state Sm of the number array. They will move the
   number array from state Sm to Sm+1.

2. Schedule the semantic token engine start() call in the
   client._on_attach() function so that users who schedule_wrap() their
   config.on_attach() functions (like nvim-lspconfig does) can still
   disable semantic tokens by deleting the semanticTokensProvider from
   their server capabilities.

* credit to @smolck and @theHamsta for their contributions in laying the
  groundwork for this feature and for their work on some of the helper
  utility functions and tests

`willSaveWaitUntil` allows servers to respond with text edits before
saving a document. That is used by some language servers to format a
document or apply quick fixes like removing unused imports.