bug#61312: Patch for eglot: scala LSP binary name

[Eli Zaretskii]

> Date: Sun, 05 Feb 2023 21:15:48 +0000
> From:  skykanin via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> It seems that eglot expects the scala metals LSP server binary to be named 
> `metals-emacs` instead of `metals`. The included patch fixes this behaviour. 
> At least in the nix package manager the `metals` binary is simply call 
> 'metals'. However if other package managers distribute an alias for the 
> binary as 'metals-emacs' as well we could instead do something like:
> ```
> (scala-mode . ,(eglot-alternatives '("metals" "metals-emacs"))
> ```

Looking at this site:

  https://github.com/rossabaker/lsp-scala

I see this:

  (defcustom lsp-scala-server-command "metals-emacs"
    "The command to launch the Scala language server."
    :group 'lsp-scala
  :type 'file)

So maybe we do need to support both names.

João, WDYT?