`:saveas newName` changes the name of an existing buffer.
Due to the buffer re-use it skips the lsp attach phase and immediately
sends a `didSave` notification to the server.
Servers get confused about this, because they expect a `didOpen`
notification first.

Closes https://github.com/neovim/neovim/issues/18688

* refactor(lsp): use autocmd api

* refactor(lsp): inline BufWritePost and VimLeavePre callbacks

Don't need to dumplog() on each failed test because we now have test-ids
that associate log messages with tests.

Fixes https://github.com/neovim/neovim/issues/18860

Most LSP servers require the notification to correctly load the
settings and for those who don't it doesn't cause any harm.

So far this is done in lspconfig, but with the addition of vim.lsp.start
it should be part of core.

Cuts down typical run time for `plugin/lsp_spec.lua`
from 70 secs to 12 secs in ASAN CI build.

This happens in ASAN/EXIT_FREE builds where nvim waits 2000ms due to
unclosed handled. I wasn't able to pin-point the exact cause.
But these tests ran in nested context where two server/client pairs
were setup for no good reason. Moving these tests out so only one client
is being setup fixed the exit hang.

The current approach of using `on_attach` callbacks for configuring
buffers for LSP is suboptimal:

1. It does not use the standard Nvim interface for driving and hooking
   into events (i.e. autocommands)
2. There is no way for "third parties" (e.g. plugins) to hook into the
   event. This means that *all* buffer configuration must go into the
   user-supplied on_attach callback. This also makes it impossible for
   these configurations to be modular, since it all must happen in the
   same place.
3. There is currently no way to do something when a client detaches from
   a buffer (there is no `on_detach` callback).

The solution is to use the traditional method of event handling in Nvim:
autocommands. When a LSP client is attached to a buffer, fire a
`LspAttach`. Likewise, when a client detaches from a buffer fire a
`LspDetach` event.

This enables plugins to easily add LSP-specific configuration to buffers
as well as enabling users to make their own configurations more modular
(e.g. by creating multiple LspAttach autocommands that each do
something unique).

Implement filtering of actions based on the kind when passing the 'only'
parameter to code_action(). Action kinds are hierachical with a '.' as
the separator, and the filter thus allows, for example, both 'quickfix'
and 'quickfix.foo' when requestiong only 'quickfix'.

Fix https://github.com/neovim/neovim/pull/18221#issuecomment-1110179121

Adds filter and id options to filter the client to use for rename.
Similar to the recently added `format` function.

rename will use all matching clients one after another and can handle a
mix of prepareRename/rename support. Also ensures the right
`offset_encoding` is used for the `make_position_params` calls

This fixes issues where subsequent calls to vim.lsp.codelens.refresh()
would have no effect due to the buffer not getting cleared from the
active_refresh table.

Examples of how such scenarios would occur are:
  - A textDocument/codeLens result yielded an error.
  - The 'textDocument/codeLens' handler was overriden in such a way that
    it no longer called vim.lsp.codelens.on_codelens().