Fix vscode-extensions rust analyzer

[happysalada]

Motivation for this change

the package.json configuration for server path changed
https://github.com/rust-analyzer/rust-analyzer/blob/master/editors/code/package.json#L324
it must have been recently, because the plugin was working last month when I used it.
the setting is now server.path and not serverPath
I've formatted with nixpkgs-fmt as well, hope it's not a problem.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[oxalica]

Have you tested the extension after your patch applied? It seems still suffer from #132938 and doesn't work.

[happysalada]

I just tested the build and verified it generated the right package.json.
I've seen there was a patch in another PR. I'll test tomorrow to make sure.

[happysalada]

Just tested and everything is good in the world again.
(this includes the other fix, that's probably why it's working).