Add manual neutral models for java.lang

See comment in java/ql/src/Metrics/Summaries/TopJdkApis.qll

   * Note: the following top JDK APIs are not modeled with MaD:
   * `java.lang.System#getProperty(String)`: needs to be modeled by regular CodeQL matching the get and set keys to reduce FPs
   * `java.lang.System#setProperty(String,String)`: needs to be modeled by regular CodeQL matching the get and set keys to reduce FPs

Author: owen-mc

java/ql/lib/ext/java.lang.model.yml

@@ -218,9 +218,11 @@ extensions:
       - ["java.lang", "System", "currentTimeMillis", "()", "summary", "manual"]
       - ["java.lang", "System", "exit", "(int)", "summary", "manual"]
       - ["java.lang", "System", "getenv", "(String)", "summary", "manual"]
+      - ["java.lang", "System", "getProperty", "", "summary", "manual"] # needs to be modeled by regular CodeQL matching the get and set keys to reduce FPs
       - ["java.lang", "System", "identityHashCode", "(Object)", "summary", "manual"]
       - ["java.lang", "System", "lineSeparator", "()", "summary", "manual"]
       - ["java.lang", "System", "nanoTime", "()", "summary", "manual"]
+      - ["java.lang", "System", "setProperty", "", "summary", "manual"] # needs to be modeled by regular CodeQL matching the get and set keys to reduce FPs
       - ["java.lang", "Thread", "currentThread", "()", "summary", "manual"]
       - ["java.lang", "Thread", "getContextClassLoader", "()", "summary", "manual"]
       - ["java.lang", "Thread", "interrupt", "()", "summary", "manual"]