Added support for Java Flight Recorder features

[pivotal-david-osullivan]

Summary

This PR adds support for Java Flight Recorder features by adding flag -XX:StartFlightRecording=.

Support for configuring JFR via arguments is provided with optional environment variable BPL_JFR_ARGS. This accepts a comma separated list of any/all of the following arguments and their values, e.g. filename=/tmp/rec.jfr,dumponexit=true:

• disk
• dumponexit
• filename
• maxsize
• maxage
• settings
• path-to-gc-roots
• name
• delay

Also adds missing license headers to other helpers

Use Cases

Enable Java Flight Recording for analysis via JMX or jcmd tool

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[dmikusa]

I think we're on the right path. A few comments for things I think we can improve.

I also got some test errors:

> richgo test ./...
PASS | github.com/paketo-buildpacks/libjvm
PASS | github.com/paketo-buildpacks/libjvm/calc
SKIP | github.com/paketo-buildpacks/libjvm/cmd/helper	[no test files]
PASS | github.com/paketo-buildpacks/libjvm/count
     | Suite: libjvm/helper
     | Total: 70 | Focused: 0 | Pending: 0
     | ...................................................................xx.
     | Passed: 68 | Failed: 2 | Skipped: 0
FAIL | Unit (0.04s)
FAIL |     Unit/libjvm/helper (0.03s)
FAIL |             Unit/libjvm/helper/JFR/$BPL_JAVA_FLIGHT_RECORDER_ENABLED/$BPL_JFR_ARGS_is_set/returns_an_error_if_a_JFR_argument_is_empty (0.00s)
     |             jfr_test.go:62:
     |                 Expected an error to have occurred.  Got:
     |                     <nil>: nil
FAIL |             Unit/libjvm/helper/JFR/$BPL_JAVA_FLIGHT_RECORDER_ENABLED/$BPL_JFR_ARGS_is_set/returns_an_error_if_JFR_arguments_are_not_parsable (0.00s)
     |             jfr_test.go:68:
     |                 Expected an error to have occurred.  Got:
     |                     <nil>: nil
FAIL | 	github.com/paketo-buildpacks/libjvm/helper	0.242s
SKIP | github.com/paketo-buildpacks/libjvm/internal	[no test files]

I think CI is failing similarly.