phpactor: add shell completion

Shell completions are only provided for bash. This means they will also work for zsh, but not for fish

pkgs/development/tools/phpactor/default.nix

@@ -1,5 +1,6 @@
 { lib
 , fetchFromGitHub
+, installShellFiles
 , php
 }:
 
@@ -16,6 +17,13 @@ php.buildComposerProject (finalAttrs: {
 
   vendorHash = "sha256-0jvWbQubPXDhsXqEp8q5R0Y7rQX3UiccGDF3HDBeh7o=";
 
+  nativeBuildInputs = [ installShellFiles ];
+
+  postInstall = ''
+    installShellCompletion --cmd phpactor \
+      --bash <($out/bin/phpactor completion bash)
+  '';
+
   meta = {
     changelog = "https://github.com/phpactor/phpactor/releases/tag/${finalAttrs.version}";
     description = "Mainly a PHP Language Server";