karate-ui enhancements part 1

[vmchukky]

Address few items mentioned in the laundry list for the UI

• Should be able to edit and save an existing test
• Should be able to create a test from scratch. this means options to add / remove test steps (rows) should be added to the UI
• right now the result of the Postman import conversion is saved to the file system. the user should be able to preview the result of the conversion and then choose where it needs to be saved

[vmchukky]

@ptrthomas please review #480 at your convenience

[vmchukky]

@ptrthomas please review #481 at your convenience

This will address the fourth item from your initial list.

[ptrthomas]

closing, superceded by #568