[TESTBUG] Test JFR API from Java agent

Today, there is no testing of JFR API from a Java agent. There is a test caledl EvilInstrument.java, but It doesn't start JFR programmatically It only instruments JDK code that JFR also tries to instrument.

The new test:

- Should start a recording
- Commit 1 000 000 events from 5 different threads. This will fill some global buffers and provoke a chunk rotation. The events should contain:
  - stack trace
  - a class field
  - a thread field (assigned with a started thread)
  - a string field (assigned with a string of more than 20 characters)
  The above will provoke constant pools early.
- Stop the recording
- Dump the file
- Verify the file is correct (in process)
- Transfer recording over JMX to another process and verify that it is correct.

All operations should happen before the main method is started.

Using a Java agent is a common scenario for tools vendors and should explicitly be tested.