Update jetty version to 9.4.35.v20201120

Includes a fix for CVE-2020-27218 [1] that affects versions prior
to 9.4.35.v20201120.

As of: [2] new dependency was added to jetty-servlet: jetty-util-ajax.

[1] https://nvd.nist.gov/vuln/detail/CVE-2020-27218
[2] https://github.com/eclipse/jetty.project/issues/5539

Change-Id: I51549c9588f5748f36e145f8c4b347f97c08b4d8

lib/jetty/BUILD

@@ -4,7 +4,10 @@ java_library(
     name = "servlet",
     data = ["//lib:LICENSE-Apache2.0"],
     visibility = ["//visibility:public"],
-    exports = ["@jetty-servlet//jar"],
+    exports = [
+        ":util-ajax",
+        "@jetty-servlet//jar",
+    ],
     runtime_deps = [":security"],
 )
 
@@ -69,3 +72,9 @@ java_library(
     data = ["//lib:LICENSE-Apache2.0"],
     exports = ["@jetty-util//jar"],
 )
+
+java_library(
+    name = "util-ajax",
+    data = ["//lib:LICENSE-Apache2.0"],
+    exports = ["@jetty-util-ajax//jar"],
+)