Implement auto-installation of fsharp language server (#920)

* Expand lsp-fsharp-server-path

* Implement auto-installing of fsautocomplete

* Add `--background-service-enabled` as default flag

* Implement fsharp auto-install for other runtimes

* Update README

* Fix README formatting

* Add better support for windows on F# autoinstall

Author: TOTBWF