RFR(S): 8209813: [TESTBUG] rewrite JFR shell tests in Java

[mikhailo.seledtsov at oracle.com]

Please review this change that converts JFR shell tests to Java.

     JBS: https://bugs.openjdk.java.net/browse/JDK-8209813
     Webrev: http://cr.openjdk.java.net/~mseledtsov/8209813.00/index.html
     Testing:
         1. Locally: exercised affected tests locally on Linux-x64: PASS
         2. Test Cluster: jdk/jdk/jfr test run - in progress


Thank you,
Misha