More LSP information in :ALEInfo

I would like #3368 to be completed first.

`:ALEInfo` should show more information about LSP connections, in particular:

1. `:ALEInfo` should tell you what state LSP connections are in. (Probably `not connected`, `connected`, `failed`.)
2. Where possible, error messages from commands for running LSP servers should be logged.
3. `window/showMessage` messages should be logged in `:ALEInfo`. [See here](https://microsoft.github.io/language-server-protocol/specification#window_showMessage).
4. Show which features language servers support in `:ALEInfo`.
5. Show messages sent by language servers that ALE doesn't handle.