Link global eslint packages to local project

With the update to eslint 6.0.0 eslint does not support a global
installation anymore. Since a local installation is not feasible on
the gerrit-ci and will also cause issues with bazel, since the
packages will not be available locally in the sandbox, the lint_test.sh
script now links a global eslint (and eslint-plugins) installation to
the local project. This allows to use eslint 6.0.0 without having to
reinstall it in every instance of the project, which would be the case
for every build on the CI.

Change-Id: I6c41a0450a6d23860356f0e2615a45c46e9d8a89
diff --git a/polygerrit-ui/app/lint_test.sh b/polygerrit-ui/app/lint_test.sh
index 35939ba..f9459c3 100755
--- a/polygerrit-ui/app/lint_test.sh
+++ b/polygerrit-ui/app/lint_test.sh
@@ -19,4 +19,8 @@
     exit 1
 fi
 
-${eslint_bin} --ignore-pattern 'bower_components/' --ignore-pattern 'gr-linked-text' --ignore-pattern 'scripts/vendor' --ext .html,.js .
+# Linking global eslint packages to the local project. Required to use eslint plugins with a global
+# eslint installation.
+npm link eslint eslint-config-google eslint-plugin-html
+
+${eslint_bin} --ignore-pattern 'node_modules/' --ignore-pattern 'bower_components/' --ignore-pattern 'gr-linked-text' --ignore-pattern 'scripts/vendor' --ext .html,.js .