Issue-479-1: UI enhancements to handle runAll / runUpto using JavaFX Service/Task

[vmchukky]

Description

Patch to fix the pending item from #425 (comment)

Currently the threading model needs work, the status of step execution reflects only at the end of ALL steps. needs to be fixed

We were invoking runAll() / runUpto() in the Java FX Application thread, which was causing varPanel / logPanel updates to be taken up only after all steps are executed. Introduced RunService to offload these (runAll/runUpto) and free Java FX Application thread.

Also added a unit test case (not sure of what happens when running tests on a headless / no-display system). It ran fine in my local setup, will wait for the test results and then may be remove the newly added test.

• Relevant Issues : karate-ui enhancements part 1 #479
• Relevant PRs : Issue-479: karate-ui enhanced to create-new/edit-existing/save-modified features #480
• Type of change :
  • New feature
  • Bug fix for existing feature
  • Code quality improvement
  • Addition or Improvement of tests
  • Addition or Improvement of documentation

[vmchukky]

As expected, am seeing
Running com.intuit.karate.ui.ThreadTest
Exception in thread "Thread-1" java.lang.UnsupportedOperationException: Unable to open DISPLAY

Let me disable the newly added unit test (ThreadTest.java)

[ptrthomas]

this is really great work, thanks ! I'll rename the test to be a little more convenient to run in the IDE