kimai: (re-)enable Composer plugins and asset install; fix running Kimai

`composerNoPlugins = false` allow plugin from Symphony, Kimai's
dependency, to create `autoload_runtime.php`. Meanwhile, asset install
step in `postInstall` script copies certain static assets to its final
position.

Both were disabled as part of PR 459254 [^1].

[^1]: https://github.com/NixOS/nixpkgs/pull/459254 ("build-support/php:
      improve PHP builder stability")

pkgs/by-name/ki/kimai/package.nix

@@ -40,6 +40,7 @@ php.buildComposerProject2 (finalAttrs: {
 
   vendorHash = "sha256-3/LT5HjCpnO3Sz+NshrSMTujtYka0FMyT56qmiEi2t4=";
 
+  composerNoPlugins = false;
   postInstall = ''
     # Make available the console utility, as Kimai doesn't list this in
     # composer.json.
@@ -48,7 +49,7 @@ php.buildComposerProject2 (finalAttrs: {
 
     # Install bundled assets. This is normally done in the `composer install`
     # post-install script, but it's being skipped.
-    # (cd "$out"/share/php/kimai && php ./bin/console assets:install)
+    (cd "$out"/share/php/kimai && php ./bin/console assets:install)
   '';
 
   passthru.tests = {