Ref https://github.com/neovim/neovim/discussions/32015

* Cancel watcher in the "force" case.
* Cancel watcher outside the async callback. It seems nvim doesn't wait
  async jobs on quitting, leaving detached inotifywait processes.
* Clean up cancelling callbacks.

Problem:
Language server version information missing from `:checkhealth vim.lsp`.

Solution:
Store `InitializeResult.serverInfo.version` from the `initialize`
response and display for each client in `:checkhealth vim.lsp`.

Design goals/requirements:
- Default configuration of a server can be distributed across multiple sources.
  - And via RTP discovery.
- Default configuration can be specified for all servers.
- Configuration _can_ be project specific.

Solution:

- Two new API's:
  - `vim.lsp.config(name, cfg)`:
    - Used to define default configurations for servers of name.
    - Can be used like a table or called as a function.
    - Use `vim.lsp.confg('*', cfg)` to specify default config for all
      servers.
  - `vim.lsp.enable(name)`
    - Used to enable servers of name. Uses configuration defined
    via `vim.lsp.config()`.

Not essential, but adds robustness and hardening for future
changes.

Problem:
LSP module has multiple "start" interfaces.

Solution:
- Enhance vim.lsp.start
- Deprecate vim.lsp.start_client